ETH Price: $2,501.18 (+0.29%)

Transaction Decoder

Block:
18248184 at Sep-30-2023 11:20:11 AM +UTC
Transaction Fee:
0.001776644227282464 ETH $4.44
Gas Used:
228,276 Gas / 7.782877864 Gwei

Emitted Events:

49 GnosisSafeProxy.0x3d0ce9bfc3ed7d6862dbb28b2dea94561fe714a1b4d019aa8af39730d1ad7c3d( 0x3d0ce9bfc3ed7d6862dbb28b2dea94561fe714a1b4d019aa8af39730d1ad7c3d, 0x0000000000000000000000004d236e55e54ed960887659d046c60f377cca58f8, 000000000000000000000000000000000000000000000000000220e16c13b477 )
50 SoulboundCreditScore.Mint( _owner=[Sender] 0x0dfe3ee9577b4184e6eb37fade426e21a0cd2618, _tokenId=373 )
51 SoulboundCreditScore.SoulboundCreditScoreMinted( tokenId=373, identityId=2589, authorityAddress=0x5b45dAA4...2695c6Ab7, signatureDate=1696072791, paymentMethod=0x00000000...000000000, mintPrice=1000000 )

Account State Difference:

  Address   Before After State Difference Code
0x0DFe3Ee9...1a0cd2618
0.039195473602364578 Eth
Nonce: 69
0.036819726868699659 Eth
Nonce: 70
0.002375746733664919
(Titan Builder)
24.062822841905306114 Eth24.063165255905306114 Eth0.000342414
0x4d236e55...77cCa58F8
0xccfA6a84...fA8C8D7F5 34.329962849287036449 Eth34.330561951793418904 Eth0.000599102506382455

Execution Trace

ETH 0.000614080069042016 SoulboundCreditScore.mint( paymentMethod=0x0000000000000000000000000000000000000000, identityId=2589, authorityAddress=0x5b45dAA4645F79a419811dc0657FA1b2695c6Ab7, signatureDate=1696072791, signature=0xFDD1BBE0F180A87C5A1CA1A4F88DBBE1BB2B3C15BE58C39C2F7D0586BDB4A52D1493D59B3A78A19108FF4C841F730A8E2AFF34129B16E5DA5FC4022A1AB5E8321C ) => ( 373 )
  • SoulboundIdentity.ownerOf( tokenId=2589 ) => ( 0x0DFe3Ee9577B4184E6eb37FADe426E21a0cd2618 )
  • Null: 0x000...001.55c4e007( )
  • UniswapV2Router02.getAmountsIn( amountOut=1000000, path=[0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2, 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48] ) => ( amounts=[599102506382455, 1000000] )
    • UniswapV2Pair.STATICCALL( )
    • ETH 0.000599102506382455 GnosisSafeProxy.CALL( )
      • ETH 0.000599102506382455 GnosisSafe.DELEGATECALL( )
      • ETH 0.000014977562659561 0x0dfe3ee9577b4184e6eb37fade426e21a0cd2618.CALL( )
        File 1 of 6: SoulboundCreditScore
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
        import "./libraries/Errors.sol";
        import "./tokens/MasaSBTSelfSovereign.sol";
        /// @title Soulbound Credit Score
        /// @author Masa Finance
        /// @notice Soulbound token that represents a credit score.
        /// @dev Soulbound credit score, that inherits from the SBT contract.
        contract SoulboundCreditScore is MasaSBTSelfSovereign, ReentrancyGuard {
            /* ========== STATE VARIABLES =========================================== */
            /* ========== INITIALIZE ================================================ */
            /// @notice Creates a new soulbound credit score
            /// @dev Creates a new soulbound credit score, inheriting from the SBT contract.
            /// @param admin Administrator of the smart contract
            /// @param baseTokenURI Base URI of the token
            /// @param soulboundIdentity Address of the SoulboundIdentity contract
            /// @param paymentParams Payment gateway params
            constructor(
                address admin,
                string memory baseTokenURI,
                ISoulboundIdentity soulboundIdentity,
                PaymentParams memory paymentParams
            )
                MasaSBTSelfSovereign(
                    admin,
                    "Masa Credit Score",
                    "MCS",
                    baseTokenURI,
                    soulboundIdentity,
                    paymentParams
                )
                EIP712("SoulboundCreditScore", "1.0.0")
            {}
            /* ========== RESTRICTED FUNCTIONS ====================================== */
            /* ========== MUTATIVE FUNCTIONS ======================================== */
            /// @notice Mints a new SBT
            /// @dev The caller must have the MINTER role
            /// @param paymentMethod Address of token that user want to pay
            /// @param identityId TokenId of the identity to mint the NFT to
            /// @return The NFT ID of the newly minted SBT
            function mint(
                address paymentMethod,
                uint256 identityId,
                address authorityAddress,
                uint256 signatureDate,
                bytes calldata signature
            ) public payable virtual nonReentrant returns (uint256) {
                address to = soulboundIdentity.ownerOf(identityId);
                if (to != _msgSender()) revert CallerNotOwner(_msgSender());
                if (balanceOf(to) > 0) revert CreditScoreAlreadyCreated(to);
                _verify(
                    _hash(identityId, authorityAddress, signatureDate),
                    signature,
                    authorityAddress
                );
                _pay(paymentMethod, getMintPrice(paymentMethod));
                uint256 tokenId = _mintWithCounter(to);
                emit SoulboundCreditScoreMinted(
                    tokenId,
                    identityId,
                    authorityAddress,
                    signatureDate,
                    paymentMethod,
                    mintPrice
                );
                return tokenId;
            }
            /// @notice Mints a new SBT
            /// @dev The caller must have the MINTER role
            /// @param paymentMethod Address of token that user want to pay
            /// @param to The address to mint the SBT to
            /// @return The SBT ID of the newly minted SBT
            function mint(
                address paymentMethod,
                address to,
                address authorityAddress,
                uint256 signatureDate,
                bytes calldata signature
            ) external payable virtual returns (uint256) {
                uint256 identityId = soulboundIdentity.tokenOfOwner(to);
                return
                    mint(
                        paymentMethod,
                        identityId,
                        authorityAddress,
                        signatureDate,
                        signature
                    );
            }
            /* ========== VIEWS ===================================================== */
            /* ========== PRIVATE FUNCTIONS ========================================= */
            function _hash(
                uint256 identityId,
                address authorityAddress,
                uint256 signatureDate
            ) internal view returns (bytes32) {
                return
                    _hashTypedDataV4(
                        keccak256(
                            abi.encode(
                                keccak256(
                                    "MintCreditScore(uint256 identityId,address authorityAddress,uint256 signatureDate)"
                                ),
                                identityId,
                                authorityAddress,
                                signatureDate
                            )
                        )
                    );
            }
            /* ========== MODIFIERS ================================================= */
            /* ========== EVENTS ==================================================== */
            event SoulboundCreditScoreMinted(
                uint256 tokenId,
                uint256 identityId,
                address authorityAddress,
                uint256 signatureDate,
                address paymentMethod,
                uint256 mintPrice
            );
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev Contract module that helps prevent reentrant calls to a function.
         *
         * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
         * available, which can be applied to functions to make sure there are no nested
         * (reentrant) calls to them.
         *
         * Note that because there is a single `nonReentrant` guard, functions marked as
         * `nonReentrant` may not call one another. This can be worked around by making
         * those functions `private`, and then adding `external` `nonReentrant` entry
         * points to them.
         *
         * TIP: If you would like to learn more about reentrancy and alternative ways
         * to protect against it, check out our blog post
         * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
         */
        abstract contract ReentrancyGuard {
            // Booleans are more expensive than uint256 or any type that takes up a full
            // word because each write operation emits an extra SLOAD to first read the
            // slot's contents, replace the bits taken up by the boolean, and then write
            // back. This is the compiler's defense against contract upgrades and
            // pointer aliasing, and it cannot be disabled.
            // The values being non-zero value makes deployment a bit more expensive,
            // but in exchange the refund on every call to nonReentrant will be lower in
            // amount. Since refunds are capped to a percentage of the total
            // transaction's gas, it is best to keep them low in cases like this one, to
            // increase the likelihood of the full refund coming into effect.
            uint256 private constant _NOT_ENTERED = 1;
            uint256 private constant _ENTERED = 2;
            uint256 private _status;
            constructor() {
                _status = _NOT_ENTERED;
            }
            /**
             * @dev Prevents a contract from calling itself, directly or indirectly.
             * Calling a `nonReentrant` function from another `nonReentrant`
             * function is not supported. It is possible to prevent this from happening
             * by making the `nonReentrant` function external, and making it call a
             * `private` function that does the actual work.
             */
            modifier nonReentrant() {
                // On the first call to nonReentrant, _notEntered will be true
                require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
                // Any calls to nonReentrant after this point will fail
                _status = _ENTERED;
                _;
                // By storing the original value once again, a refund is triggered (see
                // https://eips.ethereum.org/EIPS/eip-2200)
                _status = _NOT_ENTERED;
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        error AddressDoesNotHaveIdentity(address to);
        error AlreadyAdded();
        error AuthorityNotExists(address authority);
        error CallerNotOwner(address caller);
        error CallerNotReader(address caller);
        error CreditScoreAlreadyCreated(address to);
        error IdentityAlreadyCreated(address to);
        error IdentityOwnerIsReader(uint256 readerIdentityId);
        error InsufficientEthAmount(uint256 amount);
        error IdentityOwnerNotTokenOwner(uint256 tokenId, uint256 ownerIdentityId);
        error InvalidPaymentMethod(address paymentMethod);
        error InvalidSignature();
        error InvalidSignatureDate(uint256 signatureDate);
        error InvalidToken(address token);
        error InvalidTokenURI(string tokenURI);
        error LinkAlreadyExists(
            address token,
            uint256 tokenId,
            uint256 readerIdentityId,
            uint256 signatureDate
        );
        error LinkAlreadyRevoked();
        error LinkDoesNotExist();
        error NameAlreadyExists(string name);
        error NameNotFound(string name);
        error NameRegisteredByOtherAccount(string name, uint256 tokenId);
        error NotAuthorized(address signer);
        error NonExistingErc20Token(address erc20token);
        error RefundFailed();
        error SameValue();
        error SBTAlreadyLinked(address token);
        error SoulNameContractNotSet();
        error TokenNotFound(uint256 tokenId);
        error TransferFailed();
        error URIAlreadyExists(string tokenURI);
        error ValidPeriodExpired(uint256 expirationDate);
        error ZeroAddress();
        error ZeroLengthName(string name);
        error ZeroYearsPeriod(uint256 yearsPeriod);
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/utils/cryptography/draft-EIP712.sol";
        import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
        import "@openzeppelin/contracts/utils/Counters.sol";
        import "../libraries/Errors.sol";
        import "../interfaces/ISoulboundIdentity.sol";
        import "../dex/PaymentGateway.sol";
        import "./MasaSBT.sol";
        /// @title MasaSBTSelfSovereign
        /// @author Masa Finance
        /// @notice Soulbound token. Non-fungible token that is not transferable.
        /// Adds a link to a SoulboundIdentity SC to let minting using the identityId
        /// Adds a payment gateway to let minting paying a fee
        /// Adds a self-sovereign protocol to let minting using an authority signature
        /// @dev Implementation of https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4105763 Soulbound token.
        abstract contract MasaSBTSelfSovereign is PaymentGateway, MasaSBT, EIP712 {
            /* ========== STATE VARIABLES =========================================== */
            using Counters for Counters.Counter;
            Counters.Counter private _tokenIdCounter;
            ISoulboundIdentity public soulboundIdentity;
            uint256 public mintPrice; // price in stable coin
            uint256 public mintPriceMASA; // price in MASA
            mapping(address => bool) public authorities;
            /* ========== INITIALIZE ================================================ */
            /// @notice Creates a new soulbound token
            /// @dev Creates a new soulbound token
            /// @param admin Administrator of the smart contract
            /// @param name Name of the token
            /// @param symbol Symbol of the token
            /// @param baseTokenURI Base URI of the token
            /// @param _soulboundIdentity Address of the SoulboundIdentity contract
            /// @param paymentParams Payment gateway params
            constructor(
                address admin,
                string memory name,
                string memory symbol,
                string memory baseTokenURI,
                ISoulboundIdentity _soulboundIdentity,
                PaymentParams memory paymentParams
            )
                PaymentGateway(admin, paymentParams)
                MasaSBT(admin, name, symbol, baseTokenURI)
            {
                if (address(_soulboundIdentity) == address(0)) revert ZeroAddress();
                soulboundIdentity = _soulboundIdentity;
            }
            /* ========== RESTRICTED FUNCTIONS ====================================== */
            /// @notice Sets the SoulboundIdentity contract address linked to this SBT
            /// @dev The caller must be the admin to call this function
            /// @param _soulboundIdentity Address of the SoulboundIdentity contract
            function setSoulboundIdentity(ISoulboundIdentity _soulboundIdentity)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (address(_soulboundIdentity) == address(0)) revert ZeroAddress();
                if (soulboundIdentity == _soulboundIdentity) revert SameValue();
                soulboundIdentity = _soulboundIdentity;
            }
            /// @notice Sets the price of minting in stable coin
            /// @dev The caller must have the admin role to call this function
            /// @param _mintPrice New price of minting in stable coin
            function setMintPrice(uint256 _mintPrice)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (mintPrice == _mintPrice) revert SameValue();
                mintPrice = _mintPrice;
            }
            /// @notice Sets the price of minting in MASA
            /// @dev The caller must have the admin role to call this function
            /// @param _mintPriceMASA New price of minting in MASA
            function setMintPriceMASA(uint256 _mintPriceMASA)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (mintPriceMASA == _mintPriceMASA) revert SameValue();
                mintPriceMASA = _mintPriceMASA;
            }
            /// @notice Adds a new authority to the list of authorities
            /// @dev The caller must have the admin role to call this function
            /// @param _authority New authority to add
            function addAuthority(address _authority)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (_authority == address(0)) revert ZeroAddress();
                if (authorities[_authority]) revert AlreadyAdded();
                authorities[_authority] = true;
            }
            /// @notice Removes an authority from the list of authorities
            /// @dev The caller must have the admin role to call this function
            /// @param _authority Authority to remove
            function removeAuthority(address _authority)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (_authority == address(0)) revert ZeroAddress();
                if (!authorities[_authority]) revert AuthorityNotExists(_authority);
                authorities[_authority] = false;
            }
            /* ========== MUTATIVE FUNCTIONS ======================================== */
            /* ========== VIEWS ===================================================== */
            /// @notice Returns the identityId owned by the given token
            /// @param tokenId Id of the token
            /// @return Id of the identity
            function getIdentityId(uint256 tokenId) external view returns (uint256) {
                address owner = super.ownerOf(tokenId);
                return soulboundIdentity.tokenOfOwner(owner);
            }
            /// @notice Returns the price for minting
            /// @dev Returns current pricing for minting
            /// @param paymentMethod Address of token that user want to pay
            /// @return Current price for minting in the given payment method
            function getMintPrice(address paymentMethod) public view returns (uint256) {
                if (mintPrice == 0 && mintPriceMASA == 0) {
                    return 0;
                } else if (
                    paymentMethod == masaToken &&
                    enabledPaymentMethod[paymentMethod] &&
                    mintPriceMASA > 0
                ) {
                    // price in MASA without conversion rate
                    return mintPriceMASA;
                } else if (
                    paymentMethod == stableCoin && enabledPaymentMethod[paymentMethod]
                ) {
                    // stable coin
                    return mintPrice;
                } else if (enabledPaymentMethod[paymentMethod]) {
                    // ETH and ERC 20 token
                    return _convertFromStableCoin(paymentMethod, mintPrice);
                } else {
                    revert InvalidPaymentMethod(paymentMethod);
                }
            }
            /// @notice Query if a contract implements an interface
            /// @dev Interface identification is specified in ERC-165.
            /// @param interfaceId The interface identifier, as specified in ERC-165
            /// @return `true` if the contract implements `interfaceId` and
            ///  `interfaceId` is not 0xffffffff, `false` otherwise
            function supportsInterface(bytes4 interfaceId)
                public
                view
                virtual
                override(AccessControl, MasaSBT)
                returns (bool)
            {
                return super.supportsInterface(interfaceId);
            }
            /* ========== PRIVATE FUNCTIONS ========================================= */
            function _verify(
                bytes32 digest,
                bytes memory signature,
                address signer
            ) internal view {
                address _signer = ECDSA.recover(digest, signature);
                if (_signer != signer) revert InvalidSignature();
                if (!authorities[_signer]) revert NotAuthorized(_signer);
            }
            function _mintWithCounter(address to) internal virtual returns (uint256) {
                uint256 tokenId = _tokenIdCounter.current();
                _tokenIdCounter.increment();
                _mint(to, tokenId);
                return tokenId;
            }
            /* ========== MODIFIERS ================================================= */
            /* ========== EVENTS ==================================================== */
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/cryptography/draft-EIP712.sol)
        pragma solidity ^0.8.0;
        import "./ECDSA.sol";
        /**
         * @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
         *
         * The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
         * thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
         * they need in their contracts using a combination of `abi.encode` and `keccak256`.
         *
         * This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
         * scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
         * ({_hashTypedDataV4}).
         *
         * The implementation of the domain separator was designed to be as efficient as possible while still properly updating
         * the chain id to protect against replay attacks on an eventual fork of the chain.
         *
         * NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
         * https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
         *
         * _Available since v3.4._
         */
        abstract contract EIP712 {
            /* solhint-disable var-name-mixedcase */
            // Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
            // invalidate the cached domain separator if the chain id changes.
            bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
            uint256 private immutable _CACHED_CHAIN_ID;
            address private immutable _CACHED_THIS;
            bytes32 private immutable _HASHED_NAME;
            bytes32 private immutable _HASHED_VERSION;
            bytes32 private immutable _TYPE_HASH;
            /* solhint-enable var-name-mixedcase */
            /**
             * @dev Initializes the domain separator and parameter caches.
             *
             * The meaning of `name` and `version` is specified in
             * https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
             *
             * - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
             * - `version`: the current major version of the signing domain.
             *
             * NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
             * contract upgrade].
             */
            constructor(string memory name, string memory version) {
                bytes32 hashedName = keccak256(bytes(name));
                bytes32 hashedVersion = keccak256(bytes(version));
                bytes32 typeHash = keccak256(
                    "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
                );
                _HASHED_NAME = hashedName;
                _HASHED_VERSION = hashedVersion;
                _CACHED_CHAIN_ID = block.chainid;
                _CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
                _CACHED_THIS = address(this);
                _TYPE_HASH = typeHash;
            }
            /**
             * @dev Returns the domain separator for the current chain.
             */
            function _domainSeparatorV4() internal view returns (bytes32) {
                if (address(this) == _CACHED_THIS && block.chainid == _CACHED_CHAIN_ID) {
                    return _CACHED_DOMAIN_SEPARATOR;
                } else {
                    return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
                }
            }
            function _buildDomainSeparator(
                bytes32 typeHash,
                bytes32 nameHash,
                bytes32 versionHash
            ) private view returns (bytes32) {
                return keccak256(abi.encode(typeHash, nameHash, versionHash, block.chainid, address(this)));
            }
            /**
             * @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
             * function returns the hash of the fully encoded EIP712 message for this domain.
             *
             * This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
             *
             * ```solidity
             * bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
             *     keccak256("Mail(address to,string contents)"),
             *     mailTo,
             *     keccak256(bytes(mailContents))
             * )));
             * address signer = ECDSA.recover(digest, signature);
             * ```
             */
            function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
                return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.7.3) (utils/cryptography/ECDSA.sol)
        pragma solidity ^0.8.0;
        import "../Strings.sol";
        /**
         * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
         *
         * These functions can be used to verify that a message was signed by the holder
         * of the private keys of a given address.
         */
        library ECDSA {
            enum RecoverError {
                NoError,
                InvalidSignature,
                InvalidSignatureLength,
                InvalidSignatureS,
                InvalidSignatureV
            }
            function _throwError(RecoverError error) private pure {
                if (error == RecoverError.NoError) {
                    return; // no error: do nothing
                } else if (error == RecoverError.InvalidSignature) {
                    revert("ECDSA: invalid signature");
                } else if (error == RecoverError.InvalidSignatureLength) {
                    revert("ECDSA: invalid signature length");
                } else if (error == RecoverError.InvalidSignatureS) {
                    revert("ECDSA: invalid signature 's' value");
                } else if (error == RecoverError.InvalidSignatureV) {
                    revert("ECDSA: invalid signature 'v' value");
                }
            }
            /**
             * @dev Returns the address that signed a hashed message (`hash`) with
             * `signature` or error string. This address can then be used for verification purposes.
             *
             * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
             * this function rejects them by requiring the `s` value to be in the lower
             * half order, and the `v` value to be either 27 or 28.
             *
             * IMPORTANT: `hash` _must_ be the result of a hash operation for the
             * verification to be secure: it is possible to craft signatures that
             * recover to arbitrary addresses for non-hashed data. A safe way to ensure
             * this is by receiving a hash of the original message (which may otherwise
             * be too long), and then calling {toEthSignedMessageHash} on it.
             *
             * Documentation for signature generation:
             * - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
             * - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
             *
             * _Available since v4.3._
             */
            function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
                if (signature.length == 65) {
                    bytes32 r;
                    bytes32 s;
                    uint8 v;
                    // ecrecover takes the signature parameters, and the only way to get them
                    // currently is to use assembly.
                    /// @solidity memory-safe-assembly
                    assembly {
                        r := mload(add(signature, 0x20))
                        s := mload(add(signature, 0x40))
                        v := byte(0, mload(add(signature, 0x60)))
                    }
                    return tryRecover(hash, v, r, s);
                } else {
                    return (address(0), RecoverError.InvalidSignatureLength);
                }
            }
            /**
             * @dev Returns the address that signed a hashed message (`hash`) with
             * `signature`. This address can then be used for verification purposes.
             *
             * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
             * this function rejects them by requiring the `s` value to be in the lower
             * half order, and the `v` value to be either 27 or 28.
             *
             * IMPORTANT: `hash` _must_ be the result of a hash operation for the
             * verification to be secure: it is possible to craft signatures that
             * recover to arbitrary addresses for non-hashed data. A safe way to ensure
             * this is by receiving a hash of the original message (which may otherwise
             * be too long), and then calling {toEthSignedMessageHash} on it.
             */
            function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
                (address recovered, RecoverError error) = tryRecover(hash, signature);
                _throwError(error);
                return recovered;
            }
            /**
             * @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
             *
             * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
             *
             * _Available since v4.3._
             */
            function tryRecover(
                bytes32 hash,
                bytes32 r,
                bytes32 vs
            ) internal pure returns (address, RecoverError) {
                bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
                uint8 v = uint8((uint256(vs) >> 255) + 27);
                return tryRecover(hash, v, r, s);
            }
            /**
             * @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
             *
             * _Available since v4.2._
             */
            function recover(
                bytes32 hash,
                bytes32 r,
                bytes32 vs
            ) internal pure returns (address) {
                (address recovered, RecoverError error) = tryRecover(hash, r, vs);
                _throwError(error);
                return recovered;
            }
            /**
             * @dev Overload of {ECDSA-tryRecover} that receives the `v`,
             * `r` and `s` signature fields separately.
             *
             * _Available since v4.3._
             */
            function tryRecover(
                bytes32 hash,
                uint8 v,
                bytes32 r,
                bytes32 s
            ) internal pure returns (address, RecoverError) {
                // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
                // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
                // the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
                // signatures from current libraries generate a unique signature with an s-value in the lower half order.
                //
                // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
                // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
                // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
                // these malleable signatures as well.
                if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
                    return (address(0), RecoverError.InvalidSignatureS);
                }
                if (v != 27 && v != 28) {
                    return (address(0), RecoverError.InvalidSignatureV);
                }
                // If the signature is valid (and not malleable), return the signer address
                address signer = ecrecover(hash, v, r, s);
                if (signer == address(0)) {
                    return (address(0), RecoverError.InvalidSignature);
                }
                return (signer, RecoverError.NoError);
            }
            /**
             * @dev Overload of {ECDSA-recover} that receives the `v`,
             * `r` and `s` signature fields separately.
             */
            function recover(
                bytes32 hash,
                uint8 v,
                bytes32 r,
                bytes32 s
            ) internal pure returns (address) {
                (address recovered, RecoverError error) = tryRecover(hash, v, r, s);
                _throwError(error);
                return recovered;
            }
            /**
             * @dev Returns an Ethereum Signed Message, created from a `hash`. This
             * produces hash corresponding to the one signed with the
             * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
             * JSON-RPC method as part of EIP-191.
             *
             * See {recover}.
             */
            function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
                // 32 is the length in bytes of hash,
                // enforced by the type signature above
                return keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
        32", hash));
            }
            /**
             * @dev Returns an Ethereum Signed Message, created from `s`. This
             * produces hash corresponding to the one signed with the
             * https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
             * JSON-RPC method as part of EIP-191.
             *
             * See {recover}.
             */
            function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
                return keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
        ", Strings.toString(s.length), s));
            }
            /**
             * @dev Returns an Ethereum Signed Typed Data, created from a
             * `domainSeparator` and a `structHash`. This produces hash corresponding
             * to the one signed with the
             * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
             * JSON-RPC method as part of EIP-712.
             *
             * See {recover}.
             */
            function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
                return keccak256(abi.encodePacked("\\x19\\x01", domainSeparator, structHash));
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/Counters.sol)
        pragma solidity ^0.8.0;
        /**
         * @title Counters
         * @author Matt Condon (@shrugs)
         * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
         * of elements in a mapping, issuing ERC721 ids, or counting request ids.
         *
         * Include with `using Counters for Counters.Counter;`
         */
        library Counters {
            struct Counter {
                // This variable should never be directly accessed by users of the library: interactions must be restricted to
                // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
                // this feature: see https://github.com/ethereum/solidity/issues/4637
                uint256 _value; // default: 0
            }
            function current(Counter storage counter) internal view returns (uint256) {
                return counter._value;
            }
            function increment(Counter storage counter) internal {
                unchecked {
                    counter._value += 1;
                }
            }
            function decrement(Counter storage counter) internal {
                uint256 value = counter._value;
                require(value > 0, "Counter: decrement overflow");
                unchecked {
                    counter._value = value - 1;
                }
            }
            function reset(Counter storage counter) internal {
                counter._value = 0;
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../tokens/SBT/ISBT.sol";
        import "./ISoulName.sol";
        interface ISoulboundIdentity is ISBT {
            function mint(address to) external returns (uint256);
            function mintIdentityWithName(
                address to,
                string memory name,
                uint256 yearsPeriod,
                string memory _tokenURI
            ) external returns (uint256);
            function getSoulName() external view returns (ISoulName);
            function tokenOfOwner(address owner) external view returns (uint256);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/access/AccessControl.sol";
        import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
        import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
        import "@openzeppelin/contracts/utils/math/SafeMath.sol";
        import "../libraries/Errors.sol";
        import "../interfaces/dex/IUniswapRouter.sol";
        /// @title Pay using a Decentralized automated market maker (AMM) when needed
        /// @author Masa Finance
        /// @notice Smart contract to call a Dex AMM smart contract to pay to a reserve wallet recipient
        /// @dev This smart contract will call the Uniswap Router interface, based on
        /// https://github.com/Uniswap/v2-periphery/blob/master/contracts/interfaces/IUniswapV2Router01.sol
        abstract contract PaymentGateway is AccessControl {
            using SafeERC20 for IERC20;
            using SafeMath for uint256;
            struct PaymentParams {
                address swapRouter; // Swap router address
                address wrappedNativeToken; // Wrapped native token address
                address stableCoin; // Stable coin to pay the fee in (USDC)
                address masaToken; // Utility token to pay the fee in (MASA)
                address reserveWallet; // Wallet that will receive the fee
            }
            /* ========== STATE VARIABLES =========================================== */
            address public swapRouter;
            address public wrappedNativeToken;
            address public stableCoin; // USDC. It also needs to be enabled as payment method, if we want to pay in USDC
            address public masaToken; // MASA. It also needs to be enabled as payment method, if we want to pay in MASA
            // enabled payment methods: ETH and ERC20 tokens
            mapping(address => bool) public enabledPaymentMethod;
            address[] public enabledPaymentMethods;
            address public reserveWallet;
            /* ========== INITIALIZE ================================================ */
            /// @notice Creates a new Dex AMM
            /// @dev Creates a new Decentralized automated market maker (AMM) smart contract,
            // that will call the Uniswap Router interface
            /// @param admin Administrator of the smart contract
            /// @param paymentParams Payment params
            constructor(address admin, PaymentParams memory paymentParams) {
                if (paymentParams.swapRouter == address(0)) revert ZeroAddress();
                if (paymentParams.wrappedNativeToken == address(0))
                    revert ZeroAddress();
                if (paymentParams.stableCoin == address(0)) revert ZeroAddress();
                if (paymentParams.reserveWallet == address(0)) revert ZeroAddress();
                _grantRole(DEFAULT_ADMIN_ROLE, admin);
                swapRouter = paymentParams.swapRouter;
                wrappedNativeToken = paymentParams.wrappedNativeToken;
                stableCoin = paymentParams.stableCoin;
                masaToken = paymentParams.masaToken;
                reserveWallet = paymentParams.reserveWallet;
            }
            /* ========== RESTRICTED FUNCTIONS ====================================== */
            /// @notice Sets the swap router address
            /// @dev The caller must have the admin role to call this function
            /// @param _swapRouter New swap router address
            function setSwapRouter(address _swapRouter)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (_swapRouter == address(0)) revert ZeroAddress();
                if (swapRouter == _swapRouter) revert SameValue();
                swapRouter = _swapRouter;
            }
            /// @notice Sets the wrapped native token address
            /// @dev The caller must have the admin role to call this function
            /// @param _wrappedNativeToken New wrapped native token address
            function setWrappedNativeToken(address _wrappedNativeToken)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (_wrappedNativeToken == address(0)) revert ZeroAddress();
                if (wrappedNativeToken == _wrappedNativeToken) revert SameValue();
                wrappedNativeToken = _wrappedNativeToken;
            }
            /// @notice Sets the stable coin to pay the fee in (USDC)
            /// @dev The caller must have the admin role to call this function
            /// @param _stableCoin New stable coin to pay the fee in
            function setStableCoin(address _stableCoin)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (_stableCoin == address(0)) revert ZeroAddress();
                if (stableCoin == _stableCoin) revert SameValue();
                stableCoin = _stableCoin;
            }
            /// @notice Sets the utility token to pay the fee in (MASA)
            /// @dev The caller must have the admin role to call this function
            /// It can be set to address(0) to disable paying in MASA
            /// @param _masaToken New utility token to pay the fee in
            function setMasaToken(address _masaToken)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (masaToken == _masaToken) revert SameValue();
                masaToken = _masaToken;
            }
            /// @notice Adds a new token as a valid payment method
            /// @dev The caller must have the admin role to call this function
            /// @param _paymentMethod New token to add
            function enablePaymentMethod(address _paymentMethod)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (enabledPaymentMethod[_paymentMethod]) revert AlreadyAdded();
                enabledPaymentMethod[_paymentMethod] = true;
                enabledPaymentMethods.push(_paymentMethod);
            }
            /// @notice Removes a token as a valid payment method
            /// @dev The caller must have the admin role to call this function
            /// @param _paymentMethod Token to remove
            function disablePaymentMethod(address _paymentMethod)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (!enabledPaymentMethod[_paymentMethod])
                    revert NonExistingErc20Token(_paymentMethod);
                enabledPaymentMethod[_paymentMethod] = false;
                for (uint256 i = 0; i < enabledPaymentMethods.length; i++) {
                    if (enabledPaymentMethods[i] == _paymentMethod) {
                        enabledPaymentMethods[i] = enabledPaymentMethods[
                            enabledPaymentMethods.length - 1
                        ];
                        enabledPaymentMethods.pop();
                        break;
                    }
                }
            }
            /// @notice Set the reserve wallet
            /// @dev The caller must have the admin role to call this function
            /// @param _reserveWallet New reserve wallet
            function setReserveWallet(address _reserveWallet)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (_reserveWallet == address(0)) revert ZeroAddress();
                if (_reserveWallet == reserveWallet) revert SameValue();
                reserveWallet = _reserveWallet;
            }
            /* ========== MUTATIVE FUNCTIONS ======================================== */
            /* ========== VIEWS ===================================================== */
            /// @notice Returns all available payment methods
            /// @dev Returns the address of all available payment methods
            /// @return Array of all enabled payment methods
            function getEnabledPaymentMethods()
                external
                view
                returns (address[] memory)
            {
                return enabledPaymentMethods;
            }
            /* ========== PRIVATE FUNCTIONS ========================================= */
            /// @notice Converts an amount from a stable coin to a payment method amount
            /// @dev This method will perform the swap between the stable coin and the
            /// payment method, and return the amount of the payment method,
            /// performing the swap if necessary
            /// @param paymentMethod Address of token that user want to pay
            /// @param amount Price to be converted in the specified payment method
            function _convertFromStableCoin(address paymentMethod, uint256 amount)
                internal
                view
                returns (uint256)
            {
                if (!enabledPaymentMethod[paymentMethod] || paymentMethod == stableCoin)
                    revert InvalidToken(paymentMethod);
                if (paymentMethod == address(0)) {
                    return _estimateSwapAmount(wrappedNativeToken, stableCoin, amount);
                } else {
                    return _estimateSwapAmount(paymentMethod, stableCoin, amount);
                }
            }
            /// @notice Performs the payment in any payment method
            /// @dev This method will transfer the funds to the reserve wallet, performing
            /// the swap if necessary
            /// @param paymentMethod Address of token that user want to pay
            /// @param amount Price to be paid in the specified payment method
            function _pay(address paymentMethod, uint256 amount) internal {
                if (amount == 0) return;
                if (!enabledPaymentMethod[paymentMethod])
                    revert InvalidPaymentMethod(paymentMethod);
                if (paymentMethod == address(0)) {
                    // ETH
                    if (msg.value < amount) revert InsufficientEthAmount(amount);
                    (bool success, ) = payable(reserveWallet).call{value: amount}("");
                    if (!success) revert TransferFailed();
                    if (msg.value > amount) {
                        // return diff
                        uint256 refund = msg.value.sub(amount);
                        (success, ) = payable(msg.sender).call{value: refund}("");
                        if (!success) revert RefundFailed();
                    }
                } else {
                    // ERC20 token, including MASA and USDC
                    IERC20(paymentMethod).safeTransferFrom(
                        msg.sender,
                        reserveWallet,
                        amount
                    );
                }
            }
            function _estimateSwapAmount(
                address _fromToken,
                address _toToken,
                uint256 _amountOut
            ) private view returns (uint256) {
                uint256[] memory amounts;
                address[] memory path;
                path = _getPathFromTokenToToken(_fromToken, _toToken);
                amounts = IUniswapRouter(swapRouter).getAmountsIn(_amountOut, path);
                return amounts[0];
            }
            function _getPathFromTokenToToken(address fromToken, address toToken)
                private
                view
                returns (address[] memory)
            {
                if (fromToken == wrappedNativeToken || toToken == wrappedNativeToken) {
                    address[] memory path = new address[](2);
                    path[0] = fromToken == wrappedNativeToken
                        ? wrappedNativeToken
                        : fromToken;
                    path[1] = toToken == wrappedNativeToken
                        ? wrappedNativeToken
                        : toToken;
                    return path;
                } else {
                    address[] memory path = new address[](3);
                    path[0] = fromToken;
                    path[1] = wrappedNativeToken;
                    path[2] = toToken;
                    return path;
                }
            }
            /* ========== MODIFIERS ================================================= */
            /* ========== EVENTS ==================================================== */
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/access/AccessControl.sol";
        import "@openzeppelin/contracts/utils/Strings.sol";
        import "../libraries/Errors.sol";
        import "../interfaces/ILinkableSBT.sol";
        import "./SBT/SBT.sol";
        import "./SBT/extensions/SBTEnumerable.sol";
        import "./SBT/extensions/SBTBurnable.sol";
        /// @title MasaSBT
        /// @author Masa Finance
        /// @notice Soulbound token. Non-fungible token that is not transferable.
        /// @dev Implementation of https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4105763 Soulbound token.
        abstract contract MasaSBT is
            SBT,
            SBTEnumerable,
            AccessControl,
            SBTBurnable,
            ILinkableSBT
        {
            /* ========== STATE VARIABLES =========================================== */
            using Strings for uint256;
            string private _baseTokenURI;
            uint256 public override addLinkPrice; // price in stable coin
            uint256 public override addLinkPriceMASA; // price in MASA
            uint256 public override queryLinkPrice; // price in stable coin
            uint256 public override queryLinkPriceMASA; // price in MASA
            /* ========== INITIALIZE ================================================ */
            /// @notice Creates a new soulbound token
            /// @dev Creates a new soulbound token
            /// @param admin Administrator of the smart contract
            /// @param name Name of the token
            /// @param symbol Symbol of the token
            /// @param baseTokenURI Base URI of the token
            constructor(
                address admin,
                string memory name,
                string memory symbol,
                string memory baseTokenURI
            ) SBT(name, symbol) {
                _grantRole(DEFAULT_ADMIN_ROLE, admin);
                _baseTokenURI = baseTokenURI;
            }
            /* ========== RESTRICTED FUNCTIONS ====================================== */
            /// @notice Sets the price for adding the link in SoulLinker in stable coin
            /// @dev The caller must have the admin role to call this function
            /// @param _addLinkPrice New price for adding the link in SoulLinker in stable coin
            function setAddLinkPrice(uint256 _addLinkPrice)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (addLinkPrice == _addLinkPrice) revert SameValue();
                addLinkPrice = _addLinkPrice;
            }
            /// @notice Sets the price for adding the link in SoulLinker in MASA
            /// @dev The caller must have the admin role to call this function
            /// @param _addLinkPriceMASA New price for adding the link in SoulLinker in MASA
            function setAddLinkPriceMASA(uint256 _addLinkPriceMASA)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (addLinkPriceMASA == _addLinkPriceMASA) revert SameValue();
                addLinkPriceMASA = _addLinkPriceMASA;
            }
            /// @notice Sets the price for reading data in SoulLinker in stable coin
            /// @dev The caller must have the admin role to call this function
            /// @param _queryLinkPrice New price for reading data in SoulLinker in stable coin
            function setQueryLinkPrice(uint256 _queryLinkPrice)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (queryLinkPrice == _queryLinkPrice) revert SameValue();
                queryLinkPrice = _queryLinkPrice;
            }
            /// @notice Sets the price for reading data in SoulLinker in MASA
            /// @dev The caller must have the admin role to call this function
            /// @param _queryLinkPriceMASA New price for reading data in SoulLinker in MASA
            function setQueryLinkPriceMASA(uint256 _queryLinkPriceMASA)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (queryLinkPriceMASA == _queryLinkPriceMASA) revert SameValue();
                queryLinkPriceMASA = _queryLinkPriceMASA;
            }
            /* ========== MUTATIVE FUNCTIONS ======================================== */
            /* ========== VIEWS ===================================================== */
            /// @notice Returns true if the token exists
            /// @dev Returns true if the token has been minted
            /// @param tokenId Token to check
            /// @return True if the token exists
            function exists(uint256 tokenId) external view returns (bool) {
                return _exists(tokenId);
            }
            /// @notice A distinct Uniform Resource Identifier (URI) for a given asset.
            /// @dev Throws if `_tokenId` is not a valid SBT. URIs are defined in RFC
            ///  3986. The URI may point to a JSON file that conforms to the "ERC721
            ///  Metadata JSON Schema".
            /// @param tokenId SBT to get the URI of
            /// @return URI of the SBT
            function tokenURI(uint256 tokenId)
                public
                view
                virtual
                override
                returns (string memory)
            {
                _requireMinted(tokenId);
                string memory baseURI = _baseURI();
                return
                    bytes(baseURI).length > 0
                        ? string(abi.encodePacked(baseURI, tokenId.toString(), ".json"))
                        : "";
            }
            /// @notice Query if a contract implements an interface
            /// @dev Interface identification is specified in ERC-165.
            /// @param interfaceId The interface identifier, as specified in ERC-165
            /// @return `true` if the contract implements `interfaceId` and
            ///  `interfaceId` is not 0xffffffff, `false` otherwise
            function supportsInterface(bytes4 interfaceId)
                public
                view
                virtual
                override(SBT, SBTEnumerable, AccessControl, IERC165)
                returns (bool)
            {
                return super.supportsInterface(interfaceId);
            }
            /* ========== PRIVATE FUNCTIONS ========================================= */
            function _baseURI() internal view virtual override returns (string memory) {
                return _baseTokenURI;
            }
            function _beforeTokenTransfer(
                address from,
                address to,
                uint256 tokenId
            ) internal virtual override(SBT, SBTEnumerable) {
                super._beforeTokenTransfer(from, to, tokenId);
            }
            /* ========== MODIFIERS ================================================= */
            /* ========== EVENTS ==================================================== */
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.7.0) (utils/Strings.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev String operations.
         */
        library Strings {
            bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
            uint8 private constant _ADDRESS_LENGTH = 20;
            /**
             * @dev Converts a `uint256` to its ASCII `string` decimal representation.
             */
            function toString(uint256 value) internal pure returns (string memory) {
                // Inspired by OraclizeAPI's implementation - MIT licence
                // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
                if (value == 0) {
                    return "0";
                }
                uint256 temp = value;
                uint256 digits;
                while (temp != 0) {
                    digits++;
                    temp /= 10;
                }
                bytes memory buffer = new bytes(digits);
                while (value != 0) {
                    digits -= 1;
                    buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
                    value /= 10;
                }
                return string(buffer);
            }
            /**
             * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
             */
            function toHexString(uint256 value) internal pure returns (string memory) {
                if (value == 0) {
                    return "0x00";
                }
                uint256 temp = value;
                uint256 length = 0;
                while (temp != 0) {
                    length++;
                    temp >>= 8;
                }
                return toHexString(value, length);
            }
            /**
             * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
             */
            function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
                bytes memory buffer = new bytes(2 * length + 2);
                buffer[0] = "0";
                buffer[1] = "x";
                for (uint256 i = 2 * length + 1; i > 1; --i) {
                    buffer[i] = _HEX_SYMBOLS[value & 0xf];
                    value >>= 4;
                }
                require(value == 0, "Strings: hex length insufficient");
                return string(buffer);
            }
            /**
             * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
             */
            function toHexString(address addr) internal pure returns (string memory) {
                return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/utils/introspection/IERC165.sol";
        interface ISBT is IERC165 {
            /// @dev This emits when an SBT is newly minted.
            ///  This event emits when SBTs are created
            event Mint(address indexed _owner, uint256 indexed _tokenId);
            /// @dev This emits when an SBT is burned
            ///  This event emits when SBTs are destroyed
            event Burn(address indexed _owner, uint256 indexed _tokenId);
            /// @notice Count all SBTs assigned to an owner
            /// @dev SBTs assigned to the zero address are considered invalid, and this
            ///  function throws for queries about the zero address.
            /// @param _owner An address for whom to query the balance
            /// @return The number of SBTs owned by `_owner`, possibly zero
            function balanceOf(address _owner) external view returns (uint256);
            /// @notice Find the owner of an SBT
            /// @dev SBTs assigned to zero address are considered invalid, and queries
            ///  about them do throw.
            /// @param _tokenId The identifier for an SBT
            /// @return The address of the owner of the SBT
            function ownerOf(uint256 _tokenId) external view returns (address);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        interface ISoulName {
            function mint(
                address to,
                string memory name,
                uint256 yearsPeriod,
                string memory _tokenURI
            ) external returns (uint256);
            function getExtension() external view returns (string memory);
            function isAvailable(string memory name)
                external
                view
                returns (bool available);
            function getTokenData(string memory name)
                external
                view
                returns (
                    string memory sbtName,
                    bool linked,
                    uint256 identityId,
                    uint256 tokenId,
                    uint256 expirationDate,
                    bool active
                );
            function getTokenId(string memory name) external view returns (uint256);
            function getSoulNames(address owner)
                external
                view
                returns (string[] memory sbtNames);
            function getSoulNames(uint256 identityId)
                external
                view
                returns (string[] memory sbtNames);
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev Interface of the ERC165 standard, as defined in the
         * https://eips.ethereum.org/EIPS/eip-165[EIP].
         *
         * Implementers can declare support of contract interfaces, which can then be
         * queried by others ({ERC165Checker}).
         *
         * For an implementation, see {ERC165}.
         */
        interface IERC165 {
            /**
             * @dev Returns true if this contract implements the interface defined by
             * `interfaceId`. See the corresponding
             * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
             * to learn more about how these ids are created.
             *
             * This function call must use less than 30 000 gas.
             */
            function supportsInterface(bytes4 interfaceId) external view returns (bool);
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.7.0) (access/AccessControl.sol)
        pragma solidity ^0.8.0;
        import "./IAccessControl.sol";
        import "../utils/Context.sol";
        import "../utils/Strings.sol";
        import "../utils/introspection/ERC165.sol";
        /**
         * @dev Contract module that allows children to implement role-based access
         * control mechanisms. This is a lightweight version that doesn't allow enumerating role
         * members except through off-chain means by accessing the contract event logs. Some
         * applications may benefit from on-chain enumerability, for those cases see
         * {AccessControlEnumerable}.
         *
         * Roles are referred to by their `bytes32` identifier. These should be exposed
         * in the external API and be unique. The best way to achieve this is by
         * using `public constant` hash digests:
         *
         * ```
         * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
         * ```
         *
         * Roles can be used to represent a set of permissions. To restrict access to a
         * function call, use {hasRole}:
         *
         * ```
         * function foo() public {
         *     require(hasRole(MY_ROLE, msg.sender));
         *     ...
         * }
         * ```
         *
         * Roles can be granted and revoked dynamically via the {grantRole} and
         * {revokeRole} functions. Each role has an associated admin role, and only
         * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
         *
         * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
         * that only accounts with this role will be able to grant or revoke other
         * roles. More complex role relationships can be created by using
         * {_setRoleAdmin}.
         *
         * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
         * grant and revoke this role. Extra precautions should be taken to secure
         * accounts that have been granted it.
         */
        abstract contract AccessControl is Context, IAccessControl, ERC165 {
            struct RoleData {
                mapping(address => bool) members;
                bytes32 adminRole;
            }
            mapping(bytes32 => RoleData) private _roles;
            bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
            /**
             * @dev Modifier that checks that an account has a specific role. Reverts
             * with a standardized message including the required role.
             *
             * The format of the revert reason is given by the following regular expression:
             *
             *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
             *
             * _Available since v4.1._
             */
            modifier onlyRole(bytes32 role) {
                _checkRole(role);
                _;
            }
            /**
             * @dev See {IERC165-supportsInterface}.
             */
            function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
                return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
            }
            /**
             * @dev Returns `true` if `account` has been granted `role`.
             */
            function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
                return _roles[role].members[account];
            }
            /**
             * @dev Revert with a standard message if `_msgSender()` is missing `role`.
             * Overriding this function changes the behavior of the {onlyRole} modifier.
             *
             * Format of the revert message is described in {_checkRole}.
             *
             * _Available since v4.6._
             */
            function _checkRole(bytes32 role) internal view virtual {
                _checkRole(role, _msgSender());
            }
            /**
             * @dev Revert with a standard message if `account` is missing `role`.
             *
             * The format of the revert reason is given by the following regular expression:
             *
             *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
             */
            function _checkRole(bytes32 role, address account) internal view virtual {
                if (!hasRole(role, account)) {
                    revert(
                        string(
                            abi.encodePacked(
                                "AccessControl: account ",
                                Strings.toHexString(uint160(account), 20),
                                " is missing role ",
                                Strings.toHexString(uint256(role), 32)
                            )
                        )
                    );
                }
            }
            /**
             * @dev Returns the admin role that controls `role`. See {grantRole} and
             * {revokeRole}.
             *
             * To change a role's admin, use {_setRoleAdmin}.
             */
            function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
                return _roles[role].adminRole;
            }
            /**
             * @dev Grants `role` to `account`.
             *
             * If `account` had not been already granted `role`, emits a {RoleGranted}
             * event.
             *
             * Requirements:
             *
             * - the caller must have ``role``'s admin role.
             *
             * May emit a {RoleGranted} event.
             */
            function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
                _grantRole(role, account);
            }
            /**
             * @dev Revokes `role` from `account`.
             *
             * If `account` had been granted `role`, emits a {RoleRevoked} event.
             *
             * Requirements:
             *
             * - the caller must have ``role``'s admin role.
             *
             * May emit a {RoleRevoked} event.
             */
            function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
                _revokeRole(role, account);
            }
            /**
             * @dev Revokes `role` from the calling account.
             *
             * Roles are often managed via {grantRole} and {revokeRole}: this function's
             * purpose is to provide a mechanism for accounts to lose their privileges
             * if they are compromised (such as when a trusted device is misplaced).
             *
             * If the calling account had been revoked `role`, emits a {RoleRevoked}
             * event.
             *
             * Requirements:
             *
             * - the caller must be `account`.
             *
             * May emit a {RoleRevoked} event.
             */
            function renounceRole(bytes32 role, address account) public virtual override {
                require(account == _msgSender(), "AccessControl: can only renounce roles for self");
                _revokeRole(role, account);
            }
            /**
             * @dev Grants `role` to `account`.
             *
             * If `account` had not been already granted `role`, emits a {RoleGranted}
             * event. Note that unlike {grantRole}, this function doesn't perform any
             * checks on the calling account.
             *
             * May emit a {RoleGranted} event.
             *
             * [WARNING]
             * ====
             * This function should only be called from the constructor when setting
             * up the initial roles for the system.
             *
             * Using this function in any other way is effectively circumventing the admin
             * system imposed by {AccessControl}.
             * ====
             *
             * NOTE: This function is deprecated in favor of {_grantRole}.
             */
            function _setupRole(bytes32 role, address account) internal virtual {
                _grantRole(role, account);
            }
            /**
             * @dev Sets `adminRole` as ``role``'s admin role.
             *
             * Emits a {RoleAdminChanged} event.
             */
            function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
                bytes32 previousAdminRole = getRoleAdmin(role);
                _roles[role].adminRole = adminRole;
                emit RoleAdminChanged(role, previousAdminRole, adminRole);
            }
            /**
             * @dev Grants `role` to `account`.
             *
             * Internal function without access restriction.
             *
             * May emit a {RoleGranted} event.
             */
            function _grantRole(bytes32 role, address account) internal virtual {
                if (!hasRole(role, account)) {
                    _roles[role].members[account] = true;
                    emit RoleGranted(role, account, _msgSender());
                }
            }
            /**
             * @dev Revokes `role` from `account`.
             *
             * Internal function without access restriction.
             *
             * May emit a {RoleRevoked} event.
             */
            function _revokeRole(bytes32 role, address account) internal virtual {
                if (hasRole(role, account)) {
                    _roles[role].members[account] = false;
                    emit RoleRevoked(role, account, _msgSender());
                }
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev Interface of the ERC20 standard as defined in the EIP.
         */
        interface IERC20 {
            /**
             * @dev Emitted when `value` tokens are moved from one account (`from`) to
             * another (`to`).
             *
             * Note that `value` may be zero.
             */
            event Transfer(address indexed from, address indexed to, uint256 value);
            /**
             * @dev Emitted when the allowance of a `spender` for an `owner` is set by
             * a call to {approve}. `value` is the new allowance.
             */
            event Approval(address indexed owner, address indexed spender, uint256 value);
            /**
             * @dev Returns the amount of tokens in existence.
             */
            function totalSupply() external view returns (uint256);
            /**
             * @dev Returns the amount of tokens owned by `account`.
             */
            function balanceOf(address account) external view returns (uint256);
            /**
             * @dev Moves `amount` tokens from the caller's account to `to`.
             *
             * Returns a boolean value indicating whether the operation succeeded.
             *
             * Emits a {Transfer} event.
             */
            function transfer(address to, uint256 amount) external returns (bool);
            /**
             * @dev Returns the remaining number of tokens that `spender` will be
             * allowed to spend on behalf of `owner` through {transferFrom}. This is
             * zero by default.
             *
             * This value changes when {approve} or {transferFrom} are called.
             */
            function allowance(address owner, address spender) external view returns (uint256);
            /**
             * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
             *
             * Returns a boolean value indicating whether the operation succeeded.
             *
             * IMPORTANT: Beware that changing an allowance with this method brings the risk
             * that someone may use both the old and the new allowance by unfortunate
             * transaction ordering. One possible solution to mitigate this race
             * condition is to first reduce the spender's allowance to 0 and set the
             * desired value afterwards:
             * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
             *
             * Emits an {Approval} event.
             */
            function approve(address spender, uint256 amount) external returns (bool);
            /**
             * @dev Moves `amount` tokens from `from` to `to` using the
             * allowance mechanism. `amount` is then deducted from the caller's
             * allowance.
             *
             * Returns a boolean value indicating whether the operation succeeded.
             *
             * Emits a {Transfer} event.
             */
            function transferFrom(
                address from,
                address to,
                uint256 amount
            ) external returns (bool);
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/utils/SafeERC20.sol)
        pragma solidity ^0.8.0;
        import "../IERC20.sol";
        import "../extensions/draft-IERC20Permit.sol";
        import "../../../utils/Address.sol";
        /**
         * @title SafeERC20
         * @dev Wrappers around ERC20 operations that throw on failure (when the token
         * contract returns false). Tokens that return no value (and instead revert or
         * throw on failure) are also supported, non-reverting calls are assumed to be
         * successful.
         * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
         * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
         */
        library SafeERC20 {
            using Address for address;
            function safeTransfer(
                IERC20 token,
                address to,
                uint256 value
            ) internal {
                _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
            }
            function safeTransferFrom(
                IERC20 token,
                address from,
                address to,
                uint256 value
            ) internal {
                _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
            }
            /**
             * @dev Deprecated. This function has issues similar to the ones found in
             * {IERC20-approve}, and its usage is discouraged.
             *
             * Whenever possible, use {safeIncreaseAllowance} and
             * {safeDecreaseAllowance} instead.
             */
            function safeApprove(
                IERC20 token,
                address spender,
                uint256 value
            ) internal {
                // safeApprove should only be called when setting an initial allowance,
                // or when resetting it to zero. To increase and decrease it, use
                // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
                require(
                    (value == 0) || (token.allowance(address(this), spender) == 0),
                    "SafeERC20: approve from non-zero to non-zero allowance"
                );
                _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
            }
            function safeIncreaseAllowance(
                IERC20 token,
                address spender,
                uint256 value
            ) internal {
                uint256 newAllowance = token.allowance(address(this), spender) + value;
                _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
            }
            function safeDecreaseAllowance(
                IERC20 token,
                address spender,
                uint256 value
            ) internal {
                unchecked {
                    uint256 oldAllowance = token.allowance(address(this), spender);
                    require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
                    uint256 newAllowance = oldAllowance - value;
                    _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
                }
            }
            function safePermit(
                IERC20Permit token,
                address owner,
                address spender,
                uint256 value,
                uint256 deadline,
                uint8 v,
                bytes32 r,
                bytes32 s
            ) internal {
                uint256 nonceBefore = token.nonces(owner);
                token.permit(owner, spender, value, deadline, v, r, s);
                uint256 nonceAfter = token.nonces(owner);
                require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
            }
            /**
             * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
             * on the return value: the return value is optional (but if data is returned, it must not be false).
             * @param token The token targeted by the call.
             * @param data The call data (encoded using abi.encode or one of its variants).
             */
            function _callOptionalReturn(IERC20 token, bytes memory data) private {
                // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
                // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
                // the target address contains contract code and also asserts for success in the low-level call.
                bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
                if (returndata.length > 0) {
                    // Return data is optional
                    require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
                }
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)
        pragma solidity ^0.8.0;
        // CAUTION
        // This version of SafeMath should only be used with Solidity 0.8 or later,
        // because it relies on the compiler's built in overflow checks.
        /**
         * @dev Wrappers over Solidity's arithmetic operations.
         *
         * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
         * now has built in overflow checking.
         */
        library SafeMath {
            /**
             * @dev Returns the addition of two unsigned integers, with an overflow flag.
             *
             * _Available since v3.4._
             */
            function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                unchecked {
                    uint256 c = a + b;
                    if (c < a) return (false, 0);
                    return (true, c);
                }
            }
            /**
             * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
             *
             * _Available since v3.4._
             */
            function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                unchecked {
                    if (b > a) return (false, 0);
                    return (true, a - b);
                }
            }
            /**
             * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
             *
             * _Available since v3.4._
             */
            function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                unchecked {
                    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
                    // benefit is lost if 'b' is also tested.
                    // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
                    if (a == 0) return (true, 0);
                    uint256 c = a * b;
                    if (c / a != b) return (false, 0);
                    return (true, c);
                }
            }
            /**
             * @dev Returns the division of two unsigned integers, with a division by zero flag.
             *
             * _Available since v3.4._
             */
            function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                unchecked {
                    if (b == 0) return (false, 0);
                    return (true, a / b);
                }
            }
            /**
             * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
             *
             * _Available since v3.4._
             */
            function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                unchecked {
                    if (b == 0) return (false, 0);
                    return (true, a % b);
                }
            }
            /**
             * @dev Returns the addition of two unsigned integers, reverting on
             * overflow.
             *
             * Counterpart to Solidity's `+` operator.
             *
             * Requirements:
             *
             * - Addition cannot overflow.
             */
            function add(uint256 a, uint256 b) internal pure returns (uint256) {
                return a + b;
            }
            /**
             * @dev Returns the subtraction of two unsigned integers, reverting on
             * overflow (when the result is negative).
             *
             * Counterpart to Solidity's `-` operator.
             *
             * Requirements:
             *
             * - Subtraction cannot overflow.
             */
            function sub(uint256 a, uint256 b) internal pure returns (uint256) {
                return a - b;
            }
            /**
             * @dev Returns the multiplication of two unsigned integers, reverting on
             * overflow.
             *
             * Counterpart to Solidity's `*` operator.
             *
             * Requirements:
             *
             * - Multiplication cannot overflow.
             */
            function mul(uint256 a, uint256 b) internal pure returns (uint256) {
                return a * b;
            }
            /**
             * @dev Returns the integer division of two unsigned integers, reverting on
             * division by zero. The result is rounded towards zero.
             *
             * Counterpart to Solidity's `/` operator.
             *
             * Requirements:
             *
             * - The divisor cannot be zero.
             */
            function div(uint256 a, uint256 b) internal pure returns (uint256) {
                return a / b;
            }
            /**
             * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
             * reverting when dividing by zero.
             *
             * Counterpart to Solidity's `%` operator. This function uses a `revert`
             * opcode (which leaves remaining gas untouched) while Solidity uses an
             * invalid opcode to revert (consuming all remaining gas).
             *
             * Requirements:
             *
             * - The divisor cannot be zero.
             */
            function mod(uint256 a, uint256 b) internal pure returns (uint256) {
                return a % b;
            }
            /**
             * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
             * overflow (when the result is negative).
             *
             * CAUTION: This function is deprecated because it requires allocating memory for the error
             * message unnecessarily. For custom revert reasons use {trySub}.
             *
             * Counterpart to Solidity's `-` operator.
             *
             * Requirements:
             *
             * - Subtraction cannot overflow.
             */
            function sub(
                uint256 a,
                uint256 b,
                string memory errorMessage
            ) internal pure returns (uint256) {
                unchecked {
                    require(b <= a, errorMessage);
                    return a - b;
                }
            }
            /**
             * @dev Returns the integer division of two unsigned integers, reverting with custom message on
             * division by zero. The result is rounded towards zero.
             *
             * Counterpart to Solidity's `/` operator. Note: this function uses a
             * `revert` opcode (which leaves remaining gas untouched) while Solidity
             * uses an invalid opcode to revert (consuming all remaining gas).
             *
             * Requirements:
             *
             * - The divisor cannot be zero.
             */
            function div(
                uint256 a,
                uint256 b,
                string memory errorMessage
            ) internal pure returns (uint256) {
                unchecked {
                    require(b > 0, errorMessage);
                    return a / b;
                }
            }
            /**
             * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
             * reverting with custom message when dividing by zero.
             *
             * CAUTION: This function is deprecated because it requires allocating memory for the error
             * message unnecessarily. For custom revert reasons use {tryMod}.
             *
             * Counterpart to Solidity's `%` operator. This function uses a `revert`
             * opcode (which leaves remaining gas untouched) while Solidity uses an
             * invalid opcode to revert (consuming all remaining gas).
             *
             * Requirements:
             *
             * - The divisor cannot be zero.
             */
            function mod(
                uint256 a,
                uint256 b,
                string memory errorMessage
            ) internal pure returns (uint256) {
                unchecked {
                    require(b > 0, errorMessage);
                    return a % b;
                }
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        /// @title Uniswap Router interface
        /// @author Masa Finance
        /// @notice Interface of the Uniswap Router contract
        /// @dev This interface is used to interact with the Uniswap Router contract,
        /// and gets the most important functions of the contract. It's based on
        /// https://github.com/Uniswap/v2-periphery/blob/master/contracts/interfaces/IUniswapV2Router01.sol
        interface IUniswapRouter {
            function swapExactTokensForTokens(
                uint256 amountIn,
                uint256 amountOutMin,
                address[] calldata path,
                address to,
                uint256 deadline
            ) external returns (uint256[] memory amounts);
            function swapExactETHForTokens(
                uint256 amountOutMin,
                address[] calldata path,
                address to,
                uint256 deadline
            ) external payable returns (uint256[] memory amounts);
            function swapExactTokensForETH(
                uint256 amountIn,
                uint256 amountOutMin,
                address[] calldata path,
                address to,
                uint256 deadline
            ) external returns (uint256[] memory amounts);
            function getAmountsOut(uint256 amountIn, address[] calldata path)
                external
                view
                returns (uint256[] memory amounts);
            function getAmountsIn(uint256 amountOut, address[] calldata path)
                external
                view
                returns (uint256[] memory amounts);
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev External interface of AccessControl declared to support ERC165 detection.
         */
        interface IAccessControl {
            /**
             * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
             *
             * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
             * {RoleAdminChanged} not being emitted signaling this.
             *
             * _Available since v3.1._
             */
            event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
            /**
             * @dev Emitted when `account` is granted `role`.
             *
             * `sender` is the account that originated the contract call, an admin role
             * bearer except when using {AccessControl-_setupRole}.
             */
            event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
            /**
             * @dev Emitted when `account` is revoked `role`.
             *
             * `sender` is the account that originated the contract call:
             *   - if using `revokeRole`, it is the admin role bearer
             *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
             */
            event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
            /**
             * @dev Returns `true` if `account` has been granted `role`.
             */
            function hasRole(bytes32 role, address account) external view returns (bool);
            /**
             * @dev Returns the admin role that controls `role`. See {grantRole} and
             * {revokeRole}.
             *
             * To change a role's admin, use {AccessControl-_setRoleAdmin}.
             */
            function getRoleAdmin(bytes32 role) external view returns (bytes32);
            /**
             * @dev Grants `role` to `account`.
             *
             * If `account` had not been already granted `role`, emits a {RoleGranted}
             * event.
             *
             * Requirements:
             *
             * - the caller must have ``role``'s admin role.
             */
            function grantRole(bytes32 role, address account) external;
            /**
             * @dev Revokes `role` from `account`.
             *
             * If `account` had been granted `role`, emits a {RoleRevoked} event.
             *
             * Requirements:
             *
             * - the caller must have ``role``'s admin role.
             */
            function revokeRole(bytes32 role, address account) external;
            /**
             * @dev Revokes `role` from the calling account.
             *
             * Roles are often managed via {grantRole} and {revokeRole}: this function's
             * purpose is to provide a mechanism for accounts to lose their privileges
             * if they are compromised (such as when a trusted device is misplaced).
             *
             * If the calling account had been granted `role`, emits a {RoleRevoked}
             * event.
             *
             * Requirements:
             *
             * - the caller must be `account`.
             */
            function renounceRole(bytes32 role, address account) external;
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev Provides information about the current execution context, including the
         * sender of the transaction and its data. While these are generally available
         * via msg.sender and msg.data, they should not be accessed in such a direct
         * manner, since when dealing with meta-transactions the account sending and
         * paying for execution may not be the actual sender (as far as an application
         * is concerned).
         *
         * This contract is only required for intermediate, library-like contracts.
         */
        abstract contract Context {
            function _msgSender() internal view virtual returns (address) {
                return msg.sender;
            }
            function _msgData() internal view virtual returns (bytes calldata) {
                return msg.data;
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)
        pragma solidity ^0.8.0;
        import "./IERC165.sol";
        /**
         * @dev Implementation of the {IERC165} interface.
         *
         * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
         * for the additional interface id that will be supported. For example:
         *
         * ```solidity
         * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
         *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
         * }
         * ```
         *
         * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
         */
        abstract contract ERC165 is IERC165 {
            /**
             * @dev See {IERC165-supportsInterface}.
             */
            function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
                return interfaceId == type(IERC165).interfaceId;
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
         * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
         *
         * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
         * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
         * need to send a transaction, and thus is not required to hold Ether at all.
         */
        interface IERC20Permit {
            /**
             * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
             * given ``owner``'s signed approval.
             *
             * IMPORTANT: The same issues {IERC20-approve} has related to transaction
             * ordering also apply here.
             *
             * Emits an {Approval} event.
             *
             * Requirements:
             *
             * - `spender` cannot be the zero address.
             * - `deadline` must be a timestamp in the future.
             * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
             * over the EIP712-formatted function arguments.
             * - the signature must use ``owner``'s current nonce (see {nonces}).
             *
             * For more information on the signature format, see the
             * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
             * section].
             */
            function permit(
                address owner,
                address spender,
                uint256 value,
                uint256 deadline,
                uint8 v,
                bytes32 r,
                bytes32 s
            ) external;
            /**
             * @dev Returns the current nonce for `owner`. This value must be
             * included whenever a signature is generated for {permit}.
             *
             * Every successful call to {permit} increases ``owner``'s nonce by one. This
             * prevents a signature from being used multiple times.
             */
            function nonces(address owner) external view returns (uint256);
            /**
             * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
             */
            // solhint-disable-next-line func-name-mixedcase
            function DOMAIN_SEPARATOR() external view returns (bytes32);
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.7.0) (utils/Address.sol)
        pragma solidity ^0.8.1;
        /**
         * @dev Collection of functions related to the address type
         */
        library Address {
            /**
             * @dev Returns true if `account` is a contract.
             *
             * [IMPORTANT]
             * ====
             * It is unsafe to assume that an address for which this function returns
             * false is an externally-owned account (EOA) and not a contract.
             *
             * Among others, `isContract` will return false for the following
             * types of addresses:
             *
             *  - an externally-owned account
             *  - a contract in construction
             *  - an address where a contract will be created
             *  - an address where a contract lived, but was destroyed
             * ====
             *
             * [IMPORTANT]
             * ====
             * You shouldn't rely on `isContract` to protect against flash loan attacks!
             *
             * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
             * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
             * constructor.
             * ====
             */
            function isContract(address account) internal view returns (bool) {
                // This method relies on extcodesize/address.code.length, which returns 0
                // for contracts in construction, since the code is only stored at the end
                // of the constructor execution.
                return account.code.length > 0;
            }
            /**
             * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
             * `recipient`, forwarding all available gas and reverting on errors.
             *
             * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
             * of certain opcodes, possibly making contracts go over the 2300 gas limit
             * imposed by `transfer`, making them unable to receive funds via
             * `transfer`. {sendValue} removes this limitation.
             *
             * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
             *
             * IMPORTANT: because control is transferred to `recipient`, care must be
             * taken to not create reentrancy vulnerabilities. Consider using
             * {ReentrancyGuard} or the
             * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
             */
            function sendValue(address payable recipient, uint256 amount) internal {
                require(address(this).balance >= amount, "Address: insufficient balance");
                (bool success, ) = recipient.call{value: amount}("");
                require(success, "Address: unable to send value, recipient may have reverted");
            }
            /**
             * @dev Performs a Solidity function call using a low level `call`. A
             * plain `call` is an unsafe replacement for a function call: use this
             * function instead.
             *
             * If `target` reverts with a revert reason, it is bubbled up by this
             * function (like regular Solidity function calls).
             *
             * Returns the raw returned data. To convert to the expected return value,
             * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
             *
             * Requirements:
             *
             * - `target` must be a contract.
             * - calling `target` with `data` must not revert.
             *
             * _Available since v3.1._
             */
            function functionCall(address target, bytes memory data) internal returns (bytes memory) {
                return functionCall(target, data, "Address: low-level call failed");
            }
            /**
             * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
             * `errorMessage` as a fallback revert reason when `target` reverts.
             *
             * _Available since v3.1._
             */
            function functionCall(
                address target,
                bytes memory data,
                string memory errorMessage
            ) internal returns (bytes memory) {
                return functionCallWithValue(target, data, 0, errorMessage);
            }
            /**
             * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
             * but also transferring `value` wei to `target`.
             *
             * Requirements:
             *
             * - the calling contract must have an ETH balance of at least `value`.
             * - the called Solidity function must be `payable`.
             *
             * _Available since v3.1._
             */
            function functionCallWithValue(
                address target,
                bytes memory data,
                uint256 value
            ) internal returns (bytes memory) {
                return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
            }
            /**
             * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
             * with `errorMessage` as a fallback revert reason when `target` reverts.
             *
             * _Available since v3.1._
             */
            function functionCallWithValue(
                address target,
                bytes memory data,
                uint256 value,
                string memory errorMessage
            ) internal returns (bytes memory) {
                require(address(this).balance >= value, "Address: insufficient balance for call");
                require(isContract(target), "Address: call to non-contract");
                (bool success, bytes memory returndata) = target.call{value: value}(data);
                return verifyCallResult(success, returndata, errorMessage);
            }
            /**
             * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
             * but performing a static call.
             *
             * _Available since v3.3._
             */
            function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
                return functionStaticCall(target, data, "Address: low-level static call failed");
            }
            /**
             * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
             * but performing a static call.
             *
             * _Available since v3.3._
             */
            function functionStaticCall(
                address target,
                bytes memory data,
                string memory errorMessage
            ) internal view returns (bytes memory) {
                require(isContract(target), "Address: static call to non-contract");
                (bool success, bytes memory returndata) = target.staticcall(data);
                return verifyCallResult(success, returndata, errorMessage);
            }
            /**
             * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
             * but performing a delegate call.
             *
             * _Available since v3.4._
             */
            function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
                return functionDelegateCall(target, data, "Address: low-level delegate call failed");
            }
            /**
             * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
             * but performing a delegate call.
             *
             * _Available since v3.4._
             */
            function functionDelegateCall(
                address target,
                bytes memory data,
                string memory errorMessage
            ) internal returns (bytes memory) {
                require(isContract(target), "Address: delegate call to non-contract");
                (bool success, bytes memory returndata) = target.delegatecall(data);
                return verifyCallResult(success, returndata, errorMessage);
            }
            /**
             * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
             * revert reason using the provided one.
             *
             * _Available since v4.3._
             */
            function verifyCallResult(
                bool success,
                bytes memory returndata,
                string memory errorMessage
            ) internal pure returns (bytes memory) {
                if (success) {
                    return returndata;
                } else {
                    // Look for revert reason and bubble it up if present
                    if (returndata.length > 0) {
                        // The easiest way to bubble the revert reason is using memory via assembly
                        /// @solidity memory-safe-assembly
                        assembly {
                            let returndata_size := mload(returndata)
                            revert(add(32, returndata), returndata_size)
                        }
                    } else {
                        revert(errorMessage);
                    }
                }
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../tokens/SBT/ISBT.sol";
        interface ILinkableSBT is ISBT {
            function addLinkPrice() external view returns (uint256);
            function addLinkPriceMASA() external view returns (uint256);
            function queryLinkPrice() external view returns (uint256);
            function queryLinkPriceMASA() external view returns (uint256);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
        import "@openzeppelin/contracts/utils/Context.sol";
        import "@openzeppelin/contracts/utils/Strings.sol";
        import "./ISBT.sol";
        import "./extensions/ISBTMetadata.sol";
        /// @title SBT
        /// @author Masa Finance
        /// @notice Soulbound token is an NFT token that is not transferable.
        contract SBT is Context, ERC165, ISBT, ISBTMetadata {
            using Strings for uint256;
            // Token name
            string private _name;
            // Token symbol
            string private _symbol;
            // Mapping from token ID to owner address
            mapping(uint256 => address) private _owners;
            // Mapping owner address to token count
            mapping(address => uint256) private _balances;
            /**
             * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
             */
            constructor(string memory name_, string memory symbol_) {
                _name = name_;
                _symbol = symbol_;
            }
            /**
             * @dev See {IERC165-supportsInterface}.
             */
            function supportsInterface(bytes4 interfaceId)
                public
                view
                virtual
                override(ERC165, IERC165)
                returns (bool)
            {
                return
                    interfaceId == type(ISBT).interfaceId ||
                    interfaceId == type(ISBTMetadata).interfaceId ||
                    super.supportsInterface(interfaceId);
            }
            /**
             * @dev See {ISBT-balanceOf}.
             */
            function balanceOf(address owner)
                public
                view
                virtual
                override
                returns (uint256)
            {
                require(owner != address(0), "SBT: address zero is not a valid owner");
                return _balances[owner];
            }
            /**
             * @dev See {ISBT-ownerOf}.
             */
            function ownerOf(uint256 tokenId)
                public
                view
                virtual
                override
                returns (address)
            {
                address owner = _owners[tokenId];
                require(owner != address(0), "SBT: invalid token ID");
                return owner;
            }
            /**
             * @dev See {ISBTMetadata-name}.
             */
            function name() public view virtual override returns (string memory) {
                return _name;
            }
            /**
             * @dev See {ISBTMetadata-symbol}.
             */
            function symbol() public view virtual override returns (string memory) {
                return _symbol;
            }
            /**
             * @dev See {ISBTMetadata-tokenURI}.
             */
            function tokenURI(uint256 tokenId)
                public
                view
                virtual
                override
                returns (string memory)
            {
                _requireMinted(tokenId);
                string memory baseURI = _baseURI();
                return
                    bytes(baseURI).length > 0
                        ? string(abi.encodePacked(baseURI, tokenId.toString()))
                        : "";
            }
            /**
             * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
             * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
             * by default, can be overridden in child contracts.
             */
            function _baseURI() internal view virtual returns (string memory) {
                return "";
            }
            /**
             * @dev Returns whether `spender` is allowed to manage `tokenId`.
             *
             * Requirements:
             *
             * - `tokenId` must exist.
             */
            function _isOwner(address spender, uint256 tokenId)
                internal
                view
                virtual
                returns (bool)
            {
                address owner = SBT.ownerOf(tokenId);
                return (spender == owner);
            }
            /**
             * @dev Returns whether `tokenId` exists.
             *
             * Tokens can be managed by their owner.
             *
             * Tokens start existing when they are minted (`_mint`),
             * and stop existing when they are burned (`_burn`).
             */
            function _exists(uint256 tokenId) internal view virtual returns (bool) {
                return _owners[tokenId] != address(0);
            }
            /**
             * @dev Mints `tokenId` and transfers it to `to`.
             *
             * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
             *
             * Requirements:
             *
             * - `tokenId` must not exist.
             * - `to` cannot be the zero address.
             *
             * Emits a {Mint} event.
             */
            function _mint(address to, uint256 tokenId) internal virtual {
                require(to != address(0), "SBT: mint to the zero address");
                require(!_exists(tokenId), "SBT: token already minted");
                _beforeTokenTransfer(address(0), to, tokenId);
                _balances[to] += 1;
                _owners[tokenId] = to;
                emit Mint(to, tokenId);
                _afterTokenTransfer(address(0), to, tokenId);
            }
            /**
             * @dev Destroys `tokenId`.
             *
             * Requirements:
             * - `tokenId` must exist.
             *
             * Emits a {Burn} event.
             */
            function _burn(uint256 tokenId) internal virtual {
                address owner = SBT.ownerOf(tokenId);
                _beforeTokenTransfer(owner, address(0), tokenId);
                _balances[owner] -= 1;
                delete _owners[tokenId];
                emit Burn(owner, tokenId);
                _afterTokenTransfer(owner, address(0), tokenId);
            }
            /**
             * @dev Reverts if the `tokenId` has not been minted yet.
             */
            function _requireMinted(uint256 tokenId) internal view virtual {
                require(_exists(tokenId), "SBT: invalid token ID");
            }
            /**
             * @dev Hook that is called before any token minting/burning
             *
             * Calling conditions:
             *
             * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
             * transferred to `to`.
             * - When `from` is zero, `tokenId` will be minted for `to`.
             * - When `to` is zero, ``from``'s `tokenId` will be burned.
             * - `from` and `to` are never both zero.
             *
             * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
             */
            function _beforeTokenTransfer(
                address,
                address,
                uint256
            ) internal virtual {}
            /**
             * @dev Hook that is called after any minting/burning of tokens
             *
             * Calling conditions:
             * - when `from` and `to` are both non-zero.
             * - `from` and `to` are never both zero.
             *
             * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
             */
            function _afterTokenTransfer(
                address,
                address,
                uint256
            ) internal virtual {}
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../SBT.sol";
        import "./ISBTEnumerable.sol";
        /**
         * @dev This implements an optional extension of {SBT} defined in the EIP that adds
         * enumerability of all the token ids in the contract as well as all token ids owned by each
         * account.
         */
        abstract contract SBTEnumerable is SBT, ISBTEnumerable {
            // Mapping from owner to list of owned token IDs
            mapping(address => mapping(uint256 => uint256)) private _ownedTokens;
            // Mapping from token ID to index of the owner tokens list
            mapping(uint256 => uint256) private _ownedTokensIndex;
            // Array with all token ids, used for enumeration
            uint256[] private _allTokens;
            // Mapping from token id to position in the allTokens array
            mapping(uint256 => uint256) private _allTokensIndex;
            /**
             * @dev See {IERC165-supportsInterface}.
             */
            function supportsInterface(bytes4 interfaceId)
                public
                view
                virtual
                override(IERC165, SBT)
                returns (bool)
            {
                return
                    interfaceId == type(ISBTEnumerable).interfaceId ||
                    super.supportsInterface(interfaceId);
            }
            /**
             * @dev See {ISBTEnumerable-tokenOfOwnerByIndex}.
             */
            function tokenOfOwnerByIndex(address owner, uint256 index)
                public
                view
                virtual
                override
                returns (uint256)
            {
                require(
                    index < SBT.balanceOf(owner),
                    "SBTEnumerable: owner index out of bounds"
                );
                return _ownedTokens[owner][index];
            }
            /**
             * @dev See {ISBTEnumerable-totalSupply}.
             */
            function totalSupply() public view virtual override returns (uint256) {
                return _allTokens.length;
            }
            /**
             * @dev See {ISBTEnumerable-tokenByIndex}.
             */
            function tokenByIndex(uint256 index)
                public
                view
                virtual
                override
                returns (uint256)
            {
                require(
                    index < SBTEnumerable.totalSupply(),
                    "SBTEnumerable: global index out of bounds"
                );
                return _allTokens[index];
            }
            /**
             * @dev Hook that is called before any token transfer. This includes minting
             * and burning.
             *
             * Calling conditions:
             *
             * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
             * transferred to `to`.
             * - When `from` is zero, `tokenId` will be minted for `to`.
             * - When `to` is zero, ``from``'s `tokenId` will be burned.
             * - `from` cannot be the zero address.
             * - `to` cannot be the zero address.
             *
             * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
             */
            function _beforeTokenTransfer(
                address from,
                address to,
                uint256 tokenId
            ) internal virtual override {
                super._beforeTokenTransfer(from, to, tokenId);
                if (from == address(0)) {
                    _addTokenToAllTokensEnumeration(tokenId);
                } else if (from != to) {
                    _removeTokenFromOwnerEnumeration(from, tokenId);
                }
                if (to == address(0)) {
                    _removeTokenFromAllTokensEnumeration(tokenId);
                } else if (to != from) {
                    _addTokenToOwnerEnumeration(to, tokenId);
                }
            }
            /**
             * @dev Private function to add a token to this extension's ownership-tracking data structures.
             * @param to address representing the new owner of the given token ID
             * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
             */
            function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
                uint256 length = SBT.balanceOf(to);
                _ownedTokens[to][length] = tokenId;
                _ownedTokensIndex[tokenId] = length;
            }
            /**
             * @dev Private function to add a token to this extension's token tracking data structures.
             * @param tokenId uint256 ID of the token to be added to the tokens list
             */
            function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
                _allTokensIndex[tokenId] = _allTokens.length;
                _allTokens.push(tokenId);
            }
            /**
             * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
             * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
             * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
             * This has O(1) time complexity, but alters the order of the _ownedTokens array.
             * @param from address representing the previous owner of the given token ID
             * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
             */
            function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId)
                private
            {
                // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
                // then delete the last slot (swap and pop).
                uint256 lastTokenIndex = SBT.balanceOf(from) - 1;
                uint256 tokenIndex = _ownedTokensIndex[tokenId];
                // When the token to delete is the last token, the swap operation is unnecessary
                if (tokenIndex != lastTokenIndex) {
                    uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];
                    _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
                    _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
                }
                // This also deletes the contents at the last position of the array
                delete _ownedTokensIndex[tokenId];
                delete _ownedTokens[from][lastTokenIndex];
            }
            /**
             * @dev Private function to remove a token from this extension's token tracking data structures.
             * This has O(1) time complexity, but alters the order of the _allTokens array.
             * @param tokenId uint256 ID of the token to be removed from the tokens list
             */
            function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
                // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
                // then delete the last slot (swap and pop).
                uint256 lastTokenIndex = _allTokens.length - 1;
                uint256 tokenIndex = _allTokensIndex[tokenId];
                // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
                // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
                // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
                uint256 lastTokenId = _allTokens[lastTokenIndex];
                _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
                _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
                // This also deletes the contents at the last position of the array
                delete _allTokensIndex[tokenId];
                _allTokens.pop();
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/utils/Context.sol";
        import "../SBT.sol";
        /**
         * @title SBT Burnable Token
         * @dev SBT Token that can be burned (destroyed).
         */
        abstract contract SBTBurnable is Context, SBT {
            /**
             * @dev Burns `tokenId`. See {SBT-_burn}.
             *
             * Requirements:
             *
             * - The caller must own `tokenId` or be an approved operator.
             */
            function burn(uint256 tokenId) public virtual {
                //solhint-disable-next-line max-line-length
                require(
                    _isOwner(_msgSender(), tokenId),
                    "SBT: caller is not token owner"
                );
                _burn(tokenId);
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../ISBT.sol";
        /**
         * @title SBT Soulbound Token Standard, optional metadata extension
         */
        interface ISBTMetadata is ISBT {
            /**
             * @dev Returns the token collection name.
             */
            function name() external view returns (string memory);
            /**
             * @dev Returns the token collection symbol.
             */
            function symbol() external view returns (string memory);
            /**
             * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
             */
            function tokenURI(uint256 tokenId) external view returns (string memory);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../ISBT.sol";
        /**
         * @title SBT Soulbound Token Standard, optional enumeration extension
         */
        interface ISBTEnumerable is ISBT {
            /**
             * @dev Returns the total amount of tokens stored by the contract.
             */
            function totalSupply() external view returns (uint256);
            /**
             * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
             * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
             */
            function tokenOfOwnerByIndex(address owner, uint256 index)
                external
                view
                returns (uint256);
            /**
             * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
             * Use along with {totalSupply} to enumerate all tokens.
             */
            function tokenByIndex(uint256 index) external view returns (uint256);
        }
        

        File 2 of 6: GnosisSafeProxy
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        
        /// @title IProxy - Helper interface to access masterCopy of the Proxy on-chain
        /// @author Richard Meissner - <[email protected]>
        interface IProxy {
            function masterCopy() external view returns (address);
        }
        
        /// @title GnosisSafeProxy - Generic proxy contract allows to execute all transactions applying the code of a master contract.
        /// @author Stefan George - <[email protected]>
        /// @author Richard Meissner - <[email protected]>
        contract GnosisSafeProxy {
            // singleton always needs to be first declared variable, to ensure that it is at the same location in the contracts to which calls are delegated.
            // To reduce deployment costs this variable is internal and needs to be retrieved via `getStorageAt`
            address internal singleton;
        
            /// @dev Constructor function sets address of singleton contract.
            /// @param _singleton Singleton address.
            constructor(address _singleton) {
                require(_singleton != address(0), "Invalid singleton address provided");
                singleton = _singleton;
            }
        
            /// @dev Fallback function forwards all transactions and returns all received return data.
            fallback() external payable {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let _singleton := and(sload(0), 0xffffffffffffffffffffffffffffffffffffffff)
                    // 0xa619486e == keccak("masterCopy()"). The value is right padded to 32-bytes with 0s
                    if eq(calldataload(0), 0xa619486e00000000000000000000000000000000000000000000000000000000) {
                        mstore(0, _singleton)
                        return(0, 0x20)
                    }
                    calldatacopy(0, 0, calldatasize())
                    let success := delegatecall(gas(), _singleton, 0, calldatasize(), 0, 0)
                    returndatacopy(0, 0, returndatasize())
                    if eq(success, 0) {
                        revert(0, returndatasize())
                    }
                    return(0, returndatasize())
                }
            }
        }
        
        /// @title Proxy Factory - Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
        /// @author Stefan George - <[email protected]>
        contract GnosisSafeProxyFactory {
            event ProxyCreation(GnosisSafeProxy proxy, address singleton);
        
            /// @dev Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
            /// @param singleton Address of singleton contract.
            /// @param data Payload for message call sent to new proxy contract.
            function createProxy(address singleton, bytes memory data) public returns (GnosisSafeProxy proxy) {
                proxy = new GnosisSafeProxy(singleton);
                if (data.length > 0)
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        if eq(call(gas(), proxy, 0, add(data, 0x20), mload(data), 0, 0), 0) {
                            revert(0, 0)
                        }
                    }
                emit ProxyCreation(proxy, singleton);
            }
        
            /// @dev Allows to retrieve the runtime code of a deployed Proxy. This can be used to check that the expected Proxy was deployed.
            function proxyRuntimeCode() public pure returns (bytes memory) {
                return type(GnosisSafeProxy).runtimeCode;
            }
        
            /// @dev Allows to retrieve the creation code used for the Proxy deployment. With this it is easily possible to calculate predicted address.
            function proxyCreationCode() public pure returns (bytes memory) {
                return type(GnosisSafeProxy).creationCode;
            }
        
            /// @dev Allows to create new proxy contact using CREATE2 but it doesn't run the initializer.
            ///      This method is only meant as an utility to be called from other methods
            /// @param _singleton Address of singleton contract.
            /// @param initializer Payload for message call sent to new proxy contract.
            /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
            function deployProxyWithNonce(
                address _singleton,
                bytes memory initializer,
                uint256 saltNonce
            ) internal returns (GnosisSafeProxy proxy) {
                // If the initializer changes the proxy address should change too. Hashing the initializer data is cheaper than just concatinating it
                bytes32 salt = keccak256(abi.encodePacked(keccak256(initializer), saltNonce));
                bytes memory deploymentData = abi.encodePacked(type(GnosisSafeProxy).creationCode, uint256(uint160(_singleton)));
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    proxy := create2(0x0, add(0x20, deploymentData), mload(deploymentData), salt)
                }
                require(address(proxy) != address(0), "Create2 call failed");
            }
        
            /// @dev Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
            /// @param _singleton Address of singleton contract.
            /// @param initializer Payload for message call sent to new proxy contract.
            /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
            function createProxyWithNonce(
                address _singleton,
                bytes memory initializer,
                uint256 saltNonce
            ) public returns (GnosisSafeProxy proxy) {
                proxy = deployProxyWithNonce(_singleton, initializer, saltNonce);
                if (initializer.length > 0)
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        if eq(call(gas(), proxy, 0, add(initializer, 0x20), mload(initializer), 0, 0), 0) {
                            revert(0, 0)
                        }
                    }
                emit ProxyCreation(proxy, _singleton);
            }
        
            /// @dev Allows to create new proxy contact, execute a message call to the new proxy and call a specified callback within one transaction
            /// @param _singleton Address of singleton contract.
            /// @param initializer Payload for message call sent to new proxy contract.
            /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
            /// @param callback Callback that will be invoced after the new proxy contract has been successfully deployed and initialized.
            function createProxyWithCallback(
                address _singleton,
                bytes memory initializer,
                uint256 saltNonce,
                IProxyCreationCallback callback
            ) public returns (GnosisSafeProxy proxy) {
                uint256 saltNonceWithCallback = uint256(keccak256(abi.encodePacked(saltNonce, callback)));
                proxy = createProxyWithNonce(_singleton, initializer, saltNonceWithCallback);
                if (address(callback) != address(0)) callback.proxyCreated(proxy, _singleton, initializer, saltNonce);
            }
        
            /// @dev Allows to get the address for a new proxy contact created via `createProxyWithNonce`
            ///      This method is only meant for address calculation purpose when you use an initializer that would revert,
            ///      therefore the response is returned with a revert. When calling this method set `from` to the address of the proxy factory.
            /// @param _singleton Address of singleton contract.
            /// @param initializer Payload for message call sent to new proxy contract.
            /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
            function calculateCreateProxyWithNonceAddress(
                address _singleton,
                bytes calldata initializer,
                uint256 saltNonce
            ) external returns (GnosisSafeProxy proxy) {
                proxy = deployProxyWithNonce(_singleton, initializer, saltNonce);
                revert(string(abi.encodePacked(proxy)));
            }
        }
        
        interface IProxyCreationCallback {
            function proxyCreated(
                GnosisSafeProxy proxy,
                address _singleton,
                bytes calldata initializer,
                uint256 saltNonce
            ) external;
        }

        File 3 of 6: SoulboundIdentity
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
        import "./libraries/Errors.sol";
        import "./interfaces/ISoulboundIdentity.sol";
        import "./interfaces/ISoulName.sol";
        import "./tokens/MasaSBTAuthority.sol";
        /// @title Soulbound Identity
        /// @author Masa Finance
        /// @notice Soulbound token that represents an identity.
        /// @dev Soulbound identity, that inherits from the SBT contract.
        contract SoulboundIdentity is
            MasaSBTAuthority,
            ISoulboundIdentity,
            ReentrancyGuard
        {
            /* ========== STATE VARIABLES =========================================== */
            ISoulName public soulName;
            /* ========== INITIALIZE ================================================ */
            /// @notice Creates a new soulbound identity
            /// @dev Creates a new soulbound identity, inheriting from the SBT contract.
            /// @param admin Administrator of the smart contract
            /// @param baseTokenURI Base URI of the token
            constructor(address admin, string memory baseTokenURI)
                MasaSBTAuthority(admin, "Masa Identity", "MID", baseTokenURI)
            {}
            /* ========== RESTRICTED FUNCTIONS ====================================== */
            /// @notice Sets the SoulName contract address linked to this identity
            /// @dev The caller must have the admin role to call this function
            /// @param _soulName Address of the SoulName contract
            function setSoulName(ISoulName _soulName)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (address(_soulName) == address(0)) revert ZeroAddress();
                if (soulName == _soulName) revert SameValue();
                soulName = _soulName;
            }
            /* ========== MUTATIVE FUNCTIONS ======================================== */
            /// @notice Mints a new soulbound identity
            /// @dev The caller can only mint one identity per address
            /// @param to Address of the admin of the new identity
            function mint(address to) public override returns (uint256) {
                // Soulbound identity already created!
                if (balanceOf(to) > 0) revert IdentityAlreadyCreated(to);
                return _mintWithCounter(to);
            }
            /// @notice Mints a new soulbound identity with a SoulName associated to it
            /// @dev The caller can only mint one identity per address, and the name must be unique
            /// @param to Address of the admin of the new identity
            /// @param name Name of the new identity
            /// @param yearsPeriod Years of validity of the name
            /// @param _tokenURI URI of the NFT
            function mintIdentityWithName(
                address to,
                string memory name,
                uint256 yearsPeriod,
                string memory _tokenURI
            ) external override soulNameAlreadySet nonReentrant returns (uint256) {
                uint256 identityId = mint(to);
                soulName.mint(to, name, yearsPeriod, _tokenURI);
                return identityId;
            }
            /* ========== VIEWS ===================================================== */
            /// @notice Returns the address of the SoulName contract linked to this identity
            /// @dev This function returns the address of the SoulName contract linked to this identity
            /// @return Address of the SoulName contract
            function getSoulName() external view override returns (ISoulName) {
                return soulName;
            }
            /// @notice Returns the extension of the soul name
            /// @dev This function returns the extension of the soul name
            /// @return Extension of the soul name
            function getExtension() external view returns (string memory) {
                return soulName.getExtension();
            }
            /// @notice Returns the owner address of an identity
            /// @dev This function returns the owner address of the identity specified by the tokenId
            /// @param tokenId TokenId of the identity
            /// @return Address of the owner of the identity
            function ownerOf(uint256 tokenId)
                public
                view
                override(SBT, ISBT)
                returns (address)
            {
                return super.ownerOf(tokenId);
            }
            /// @notice Returns the owner address of a soul name
            /// @dev This function returns the owner address of the soul name identity specified by the name
            /// @param name Name of the soul name
            /// @return Address of the owner of the identity
            function ownerOf(string memory name)
                external
                view
                soulNameAlreadySet
                returns (address)
            {
                (, , uint256 identityId, , , ) = soulName.getTokenData(name);
                return super.ownerOf(identityId);
            }
            /// @notice Returns the URI of a soul name
            /// @dev This function returns the token URI of the soul name identity specified by the name
            /// @param name Name of the soul name
            /// @return URI of the identity associated to a soul name
            function tokenURI(string memory name)
                external
                view
                soulNameAlreadySet
                returns (string memory)
            {
                (, , uint256 identityId, , , ) = soulName.getTokenData(name);
                return super.tokenURI(identityId);
            }
            /// @notice Returns the URI of the owner of an identity
            /// @dev This function returns the token URI of the identity owned by an account
            /// @param owner Address of the owner of the identity
            /// @return URI of the identity owned by the account
            function tokenURI(address owner) external view returns (string memory) {
                uint256 tokenId = tokenOfOwner(owner);
                return super.tokenURI(tokenId);
            }
            /// @notice Returns the identity id of an account
            /// @dev This function returns the tokenId of the identity owned by an account
            /// @param owner Address of the owner of the identity
            /// @return TokenId of the identity owned by the account
            function tokenOfOwner(address owner)
                public
                view
                override
                returns (uint256)
            {
                return super.tokenOfOwnerByIndex(owner, 0);
            }
            /// @notice Checks if a soul name is available
            /// @dev This function queries if a soul name already exists and is in the available state
            /// @param name Name of the soul name
            /// @return available `true` if the soul name is available, `false` otherwise
            function isAvailable(string memory name)
                external
                view
                soulNameAlreadySet
                returns (bool available)
            {
                return soulName.isAvailable(name);
            }
            /// @notice Returns the information of a soul name
            /// @dev This function queries the information of a soul name
            /// @param name Name of the soul name
            /// @return sbtName Soul name, in upper/lower case and extension
            /// @return linked `true` if the soul name is linked, `false` otherwise
            /// @return identityId Identity id of the soul name
            /// @return tokenId SoulName id of the soul name
            /// @return expirationDate Expiration date of the soul name
            /// @return active `true` if the soul name is active, `false` otherwise
            function getTokenData(string memory name)
                external
                view
                soulNameAlreadySet
                returns (
                    string memory sbtName,
                    bool linked,
                    uint256 identityId,
                    uint256 tokenId,
                    uint256 expirationDate,
                    bool active
                )
            {
                return soulName.getTokenData(name);
            }
            /// @notice Returns all the active soul names of an account
            /// @dev This function queries all the identity names of the specified account
            /// @param owner Address of the owner of the identities
            /// @return sbtNames Array of soul names associated to the account
            function getSoulNames(address owner)
                external
                view
                soulNameAlreadySet
                returns (string[] memory sbtNames)
            {
                return soulName.getSoulNames(owner);
            }
            // SoulName -> SoulboundIdentity.tokenId
            // SoulName -> account -> SoulboundIdentity.tokenId
            /// @notice Returns all the active soul names of an account
            /// @dev This function queries all the identity names of the specified identity Id
            /// @param tokenId TokenId of the identity
            /// @return sbtNames Array of soul names associated to the identity Id
            function getSoulNames(uint256 tokenId)
                external
                view
                soulNameAlreadySet
                returns (string[] memory sbtNames)
            {
                return soulName.getSoulNames(tokenId);
            }
            /* ========== PRIVATE FUNCTIONS ========================================= */
            /* ========== MODIFIERS ================================================= */
            modifier soulNameAlreadySet() {
                if (address(soulName) == address(0)) revert SoulNameContractNotSet();
                _;
            }
            /* ========== EVENTS ==================================================== */
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev Contract module that helps prevent reentrant calls to a function.
         *
         * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
         * available, which can be applied to functions to make sure there are no nested
         * (reentrant) calls to them.
         *
         * Note that because there is a single `nonReentrant` guard, functions marked as
         * `nonReentrant` may not call one another. This can be worked around by making
         * those functions `private`, and then adding `external` `nonReentrant` entry
         * points to them.
         *
         * TIP: If you would like to learn more about reentrancy and alternative ways
         * to protect against it, check out our blog post
         * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
         */
        abstract contract ReentrancyGuard {
            // Booleans are more expensive than uint256 or any type that takes up a full
            // word because each write operation emits an extra SLOAD to first read the
            // slot's contents, replace the bits taken up by the boolean, and then write
            // back. This is the compiler's defense against contract upgrades and
            // pointer aliasing, and it cannot be disabled.
            // The values being non-zero value makes deployment a bit more expensive,
            // but in exchange the refund on every call to nonReentrant will be lower in
            // amount. Since refunds are capped to a percentage of the total
            // transaction's gas, it is best to keep them low in cases like this one, to
            // increase the likelihood of the full refund coming into effect.
            uint256 private constant _NOT_ENTERED = 1;
            uint256 private constant _ENTERED = 2;
            uint256 private _status;
            constructor() {
                _status = _NOT_ENTERED;
            }
            /**
             * @dev Prevents a contract from calling itself, directly or indirectly.
             * Calling a `nonReentrant` function from another `nonReentrant`
             * function is not supported. It is possible to prevent this from happening
             * by making the `nonReentrant` function external, and making it call a
             * `private` function that does the actual work.
             */
            modifier nonReentrant() {
                // On the first call to nonReentrant, _notEntered will be true
                require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
                // Any calls to nonReentrant after this point will fail
                _status = _ENTERED;
                _;
                // By storing the original value once again, a refund is triggered (see
                // https://eips.ethereum.org/EIPS/eip-2200)
                _status = _NOT_ENTERED;
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        error AddressDoesNotHaveIdentity(address to);
        error AlreadyAdded();
        error AuthorityNotExists(address authority);
        error CallerNotOwner(address caller);
        error CallerNotReader(address caller);
        error CreditScoreAlreadyCreated(address to);
        error IdentityAlreadyCreated(address to);
        error IdentityOwnerIsReader(uint256 readerIdentityId);
        error InsufficientEthAmount(uint256 amount);
        error IdentityOwnerNotTokenOwner(uint256 tokenId, uint256 ownerIdentityId);
        error InvalidPaymentMethod(address paymentMethod);
        error InvalidSignature();
        error InvalidSignatureDate(uint256 signatureDate);
        error InvalidToken(address token);
        error InvalidTokenURI(string tokenURI);
        error LinkAlreadyExists(
            address token,
            uint256 tokenId,
            uint256 readerIdentityId,
            uint256 signatureDate
        );
        error LinkAlreadyRevoked();
        error LinkDoesNotExist();
        error NameAlreadyExists(string name);
        error NameNotFound(string name);
        error NameRegisteredByOtherAccount(string name, uint256 tokenId);
        error NotAuthorized(address signer);
        error NonExistingErc20Token(address erc20token);
        error RefundFailed();
        error SameValue();
        error SBTAlreadyLinked(address token);
        error SoulNameContractNotSet();
        error TokenNotFound(uint256 tokenId);
        error TransferFailed();
        error URIAlreadyExists(string tokenURI);
        error ValidPeriodExpired(uint256 expirationDate);
        error ZeroAddress();
        error ZeroLengthName(string name);
        error ZeroYearsPeriod(uint256 yearsPeriod);
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../tokens/SBT/ISBT.sol";
        import "./ISoulName.sol";
        interface ISoulboundIdentity is ISBT {
            function mint(address to) external returns (uint256);
            function mintIdentityWithName(
                address to,
                string memory name,
                uint256 yearsPeriod,
                string memory _tokenURI
            ) external returns (uint256);
            function getSoulName() external view returns (ISoulName);
            function tokenOfOwner(address owner) external view returns (uint256);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        interface ISoulName {
            function mint(
                address to,
                string memory name,
                uint256 yearsPeriod,
                string memory _tokenURI
            ) external returns (uint256);
            function getExtension() external view returns (string memory);
            function isAvailable(string memory name)
                external
                view
                returns (bool available);
            function getTokenData(string memory name)
                external
                view
                returns (
                    string memory sbtName,
                    bool linked,
                    uint256 identityId,
                    uint256 tokenId,
                    uint256 expirationDate,
                    bool active
                );
            function getTokenId(string memory name) external view returns (uint256);
            function getSoulNames(address owner)
                external
                view
                returns (string[] memory sbtNames);
            function getSoulNames(uint256 identityId)
                external
                view
                returns (string[] memory sbtNames);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/utils/Counters.sol";
        import "./MasaSBT.sol";
        /// @title MasaSBT
        /// @author Masa Finance
        /// @notice Soulbound token. Non-fungible token that is not transferable.
        /// @dev Implementation of https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4105763 Soulbound token.
        abstract contract MasaSBTAuthority is MasaSBT {
            /* ========== STATE VARIABLES =========================================== */
            using Counters for Counters.Counter;
            bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
            Counters.Counter private _tokenIdCounter;
            /* ========== INITIALIZE ================================================ */
            /// @notice Creates a new soulbound token
            /// @dev Creates a new soulbound token
            /// @param admin Administrator of the smart contract
            /// @param name Name of the token
            /// @param symbol Symbol of the token
            /// @param baseTokenURI Base URI of the token
            constructor(
                address admin,
                string memory name,
                string memory symbol,
                string memory baseTokenURI
            ) MasaSBT(admin, name, symbol, baseTokenURI) {
                _grantRole(MINTER_ROLE, admin);
            }
            /* ========== RESTRICTED FUNCTIONS ====================================== */
            function _mintWithCounter(address to)
                internal
                virtual
                onlyRole(MINTER_ROLE)
                returns (uint256)
            {
                uint256 tokenId = _tokenIdCounter.current();
                _tokenIdCounter.increment();
                _mint(to, tokenId);
                return tokenId;
            }
            /* ========== MUTATIVE FUNCTIONS ======================================== */
            /* ========== VIEWS ===================================================== */
            /* ========== PRIVATE FUNCTIONS ========================================= */
            /* ========== MODIFIERS ================================================= */
            /* ========== EVENTS ==================================================== */
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/utils/introspection/IERC165.sol";
        interface ISBT is IERC165 {
            /// @dev This emits when an SBT is newly minted.
            ///  This event emits when SBTs are created
            event Mint(address indexed _owner, uint256 indexed _tokenId);
            /// @dev This emits when an SBT is burned
            ///  This event emits when SBTs are destroyed
            event Burn(address indexed _owner, uint256 indexed _tokenId);
            /// @notice Count all SBTs assigned to an owner
            /// @dev SBTs assigned to the zero address are considered invalid, and this
            ///  function throws for queries about the zero address.
            /// @param _owner An address for whom to query the balance
            /// @return The number of SBTs owned by `_owner`, possibly zero
            function balanceOf(address _owner) external view returns (uint256);
            /// @notice Find the owner of an SBT
            /// @dev SBTs assigned to zero address are considered invalid, and queries
            ///  about them do throw.
            /// @param _tokenId The identifier for an SBT
            /// @return The address of the owner of the SBT
            function ownerOf(uint256 _tokenId) external view returns (address);
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev Interface of the ERC165 standard, as defined in the
         * https://eips.ethereum.org/EIPS/eip-165[EIP].
         *
         * Implementers can declare support of contract interfaces, which can then be
         * queried by others ({ERC165Checker}).
         *
         * For an implementation, see {ERC165}.
         */
        interface IERC165 {
            /**
             * @dev Returns true if this contract implements the interface defined by
             * `interfaceId`. See the corresponding
             * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
             * to learn more about how these ids are created.
             *
             * This function call must use less than 30 000 gas.
             */
            function supportsInterface(bytes4 interfaceId) external view returns (bool);
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/Counters.sol)
        pragma solidity ^0.8.0;
        /**
         * @title Counters
         * @author Matt Condon (@shrugs)
         * @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
         * of elements in a mapping, issuing ERC721 ids, or counting request ids.
         *
         * Include with `using Counters for Counters.Counter;`
         */
        library Counters {
            struct Counter {
                // This variable should never be directly accessed by users of the library: interactions must be restricted to
                // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
                // this feature: see https://github.com/ethereum/solidity/issues/4637
                uint256 _value; // default: 0
            }
            function current(Counter storage counter) internal view returns (uint256) {
                return counter._value;
            }
            function increment(Counter storage counter) internal {
                unchecked {
                    counter._value += 1;
                }
            }
            function decrement(Counter storage counter) internal {
                uint256 value = counter._value;
                require(value > 0, "Counter: decrement overflow");
                unchecked {
                    counter._value = value - 1;
                }
            }
            function reset(Counter storage counter) internal {
                counter._value = 0;
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/access/AccessControl.sol";
        import "@openzeppelin/contracts/utils/Strings.sol";
        import "../libraries/Errors.sol";
        import "../interfaces/ILinkableSBT.sol";
        import "./SBT/SBT.sol";
        import "./SBT/extensions/SBTEnumerable.sol";
        import "./SBT/extensions/SBTBurnable.sol";
        /// @title MasaSBT
        /// @author Masa Finance
        /// @notice Soulbound token. Non-fungible token that is not transferable.
        /// @dev Implementation of https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4105763 Soulbound token.
        abstract contract MasaSBT is
            SBT,
            SBTEnumerable,
            AccessControl,
            SBTBurnable,
            ILinkableSBT
        {
            /* ========== STATE VARIABLES =========================================== */
            using Strings for uint256;
            string private _baseTokenURI;
            uint256 public override addLinkPrice; // price in stable coin
            uint256 public override addLinkPriceMASA; // price in MASA
            uint256 public override queryLinkPrice; // price in stable coin
            uint256 public override queryLinkPriceMASA; // price in MASA
            /* ========== INITIALIZE ================================================ */
            /// @notice Creates a new soulbound token
            /// @dev Creates a new soulbound token
            /// @param admin Administrator of the smart contract
            /// @param name Name of the token
            /// @param symbol Symbol of the token
            /// @param baseTokenURI Base URI of the token
            constructor(
                address admin,
                string memory name,
                string memory symbol,
                string memory baseTokenURI
            ) SBT(name, symbol) {
                _grantRole(DEFAULT_ADMIN_ROLE, admin);
                _baseTokenURI = baseTokenURI;
            }
            /* ========== RESTRICTED FUNCTIONS ====================================== */
            /// @notice Sets the price for adding the link in SoulLinker in stable coin
            /// @dev The caller must have the admin role to call this function
            /// @param _addLinkPrice New price for adding the link in SoulLinker in stable coin
            function setAddLinkPrice(uint256 _addLinkPrice)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (addLinkPrice == _addLinkPrice) revert SameValue();
                addLinkPrice = _addLinkPrice;
            }
            /// @notice Sets the price for adding the link in SoulLinker in MASA
            /// @dev The caller must have the admin role to call this function
            /// @param _addLinkPriceMASA New price for adding the link in SoulLinker in MASA
            function setAddLinkPriceMASA(uint256 _addLinkPriceMASA)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (addLinkPriceMASA == _addLinkPriceMASA) revert SameValue();
                addLinkPriceMASA = _addLinkPriceMASA;
            }
            /// @notice Sets the price for reading data in SoulLinker in stable coin
            /// @dev The caller must have the admin role to call this function
            /// @param _queryLinkPrice New price for reading data in SoulLinker in stable coin
            function setQueryLinkPrice(uint256 _queryLinkPrice)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (queryLinkPrice == _queryLinkPrice) revert SameValue();
                queryLinkPrice = _queryLinkPrice;
            }
            /// @notice Sets the price for reading data in SoulLinker in MASA
            /// @dev The caller must have the admin role to call this function
            /// @param _queryLinkPriceMASA New price for reading data in SoulLinker in MASA
            function setQueryLinkPriceMASA(uint256 _queryLinkPriceMASA)
                external
                onlyRole(DEFAULT_ADMIN_ROLE)
            {
                if (queryLinkPriceMASA == _queryLinkPriceMASA) revert SameValue();
                queryLinkPriceMASA = _queryLinkPriceMASA;
            }
            /* ========== MUTATIVE FUNCTIONS ======================================== */
            /* ========== VIEWS ===================================================== */
            /// @notice Returns true if the token exists
            /// @dev Returns true if the token has been minted
            /// @param tokenId Token to check
            /// @return True if the token exists
            function exists(uint256 tokenId) external view returns (bool) {
                return _exists(tokenId);
            }
            /// @notice A distinct Uniform Resource Identifier (URI) for a given asset.
            /// @dev Throws if `_tokenId` is not a valid SBT. URIs are defined in RFC
            ///  3986. The URI may point to a JSON file that conforms to the "ERC721
            ///  Metadata JSON Schema".
            /// @param tokenId SBT to get the URI of
            /// @return URI of the SBT
            function tokenURI(uint256 tokenId)
                public
                view
                virtual
                override
                returns (string memory)
            {
                _requireMinted(tokenId);
                string memory baseURI = _baseURI();
                return
                    bytes(baseURI).length > 0
                        ? string(abi.encodePacked(baseURI, tokenId.toString(), ".json"))
                        : "";
            }
            /// @notice Query if a contract implements an interface
            /// @dev Interface identification is specified in ERC-165.
            /// @param interfaceId The interface identifier, as specified in ERC-165
            /// @return `true` if the contract implements `interfaceId` and
            ///  `interfaceId` is not 0xffffffff, `false` otherwise
            function supportsInterface(bytes4 interfaceId)
                public
                view
                virtual
                override(SBT, SBTEnumerable, AccessControl, IERC165)
                returns (bool)
            {
                return super.supportsInterface(interfaceId);
            }
            /* ========== PRIVATE FUNCTIONS ========================================= */
            function _baseURI() internal view virtual override returns (string memory) {
                return _baseTokenURI;
            }
            function _beforeTokenTransfer(
                address from,
                address to,
                uint256 tokenId
            ) internal virtual override(SBT, SBTEnumerable) {
                super._beforeTokenTransfer(from, to, tokenId);
            }
            /* ========== MODIFIERS ================================================= */
            /* ========== EVENTS ==================================================== */
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.7.0) (access/AccessControl.sol)
        pragma solidity ^0.8.0;
        import "./IAccessControl.sol";
        import "../utils/Context.sol";
        import "../utils/Strings.sol";
        import "../utils/introspection/ERC165.sol";
        /**
         * @dev Contract module that allows children to implement role-based access
         * control mechanisms. This is a lightweight version that doesn't allow enumerating role
         * members except through off-chain means by accessing the contract event logs. Some
         * applications may benefit from on-chain enumerability, for those cases see
         * {AccessControlEnumerable}.
         *
         * Roles are referred to by their `bytes32` identifier. These should be exposed
         * in the external API and be unique. The best way to achieve this is by
         * using `public constant` hash digests:
         *
         * ```
         * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
         * ```
         *
         * Roles can be used to represent a set of permissions. To restrict access to a
         * function call, use {hasRole}:
         *
         * ```
         * function foo() public {
         *     require(hasRole(MY_ROLE, msg.sender));
         *     ...
         * }
         * ```
         *
         * Roles can be granted and revoked dynamically via the {grantRole} and
         * {revokeRole} functions. Each role has an associated admin role, and only
         * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
         *
         * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
         * that only accounts with this role will be able to grant or revoke other
         * roles. More complex role relationships can be created by using
         * {_setRoleAdmin}.
         *
         * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
         * grant and revoke this role. Extra precautions should be taken to secure
         * accounts that have been granted it.
         */
        abstract contract AccessControl is Context, IAccessControl, ERC165 {
            struct RoleData {
                mapping(address => bool) members;
                bytes32 adminRole;
            }
            mapping(bytes32 => RoleData) private _roles;
            bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
            /**
             * @dev Modifier that checks that an account has a specific role. Reverts
             * with a standardized message including the required role.
             *
             * The format of the revert reason is given by the following regular expression:
             *
             *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
             *
             * _Available since v4.1._
             */
            modifier onlyRole(bytes32 role) {
                _checkRole(role);
                _;
            }
            /**
             * @dev See {IERC165-supportsInterface}.
             */
            function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
                return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
            }
            /**
             * @dev Returns `true` if `account` has been granted `role`.
             */
            function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
                return _roles[role].members[account];
            }
            /**
             * @dev Revert with a standard message if `_msgSender()` is missing `role`.
             * Overriding this function changes the behavior of the {onlyRole} modifier.
             *
             * Format of the revert message is described in {_checkRole}.
             *
             * _Available since v4.6._
             */
            function _checkRole(bytes32 role) internal view virtual {
                _checkRole(role, _msgSender());
            }
            /**
             * @dev Revert with a standard message if `account` is missing `role`.
             *
             * The format of the revert reason is given by the following regular expression:
             *
             *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
             */
            function _checkRole(bytes32 role, address account) internal view virtual {
                if (!hasRole(role, account)) {
                    revert(
                        string(
                            abi.encodePacked(
                                "AccessControl: account ",
                                Strings.toHexString(uint160(account), 20),
                                " is missing role ",
                                Strings.toHexString(uint256(role), 32)
                            )
                        )
                    );
                }
            }
            /**
             * @dev Returns the admin role that controls `role`. See {grantRole} and
             * {revokeRole}.
             *
             * To change a role's admin, use {_setRoleAdmin}.
             */
            function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
                return _roles[role].adminRole;
            }
            /**
             * @dev Grants `role` to `account`.
             *
             * If `account` had not been already granted `role`, emits a {RoleGranted}
             * event.
             *
             * Requirements:
             *
             * - the caller must have ``role``'s admin role.
             *
             * May emit a {RoleGranted} event.
             */
            function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
                _grantRole(role, account);
            }
            /**
             * @dev Revokes `role` from `account`.
             *
             * If `account` had been granted `role`, emits a {RoleRevoked} event.
             *
             * Requirements:
             *
             * - the caller must have ``role``'s admin role.
             *
             * May emit a {RoleRevoked} event.
             */
            function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
                _revokeRole(role, account);
            }
            /**
             * @dev Revokes `role` from the calling account.
             *
             * Roles are often managed via {grantRole} and {revokeRole}: this function's
             * purpose is to provide a mechanism for accounts to lose their privileges
             * if they are compromised (such as when a trusted device is misplaced).
             *
             * If the calling account had been revoked `role`, emits a {RoleRevoked}
             * event.
             *
             * Requirements:
             *
             * - the caller must be `account`.
             *
             * May emit a {RoleRevoked} event.
             */
            function renounceRole(bytes32 role, address account) public virtual override {
                require(account == _msgSender(), "AccessControl: can only renounce roles for self");
                _revokeRole(role, account);
            }
            /**
             * @dev Grants `role` to `account`.
             *
             * If `account` had not been already granted `role`, emits a {RoleGranted}
             * event. Note that unlike {grantRole}, this function doesn't perform any
             * checks on the calling account.
             *
             * May emit a {RoleGranted} event.
             *
             * [WARNING]
             * ====
             * This function should only be called from the constructor when setting
             * up the initial roles for the system.
             *
             * Using this function in any other way is effectively circumventing the admin
             * system imposed by {AccessControl}.
             * ====
             *
             * NOTE: This function is deprecated in favor of {_grantRole}.
             */
            function _setupRole(bytes32 role, address account) internal virtual {
                _grantRole(role, account);
            }
            /**
             * @dev Sets `adminRole` as ``role``'s admin role.
             *
             * Emits a {RoleAdminChanged} event.
             */
            function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
                bytes32 previousAdminRole = getRoleAdmin(role);
                _roles[role].adminRole = adminRole;
                emit RoleAdminChanged(role, previousAdminRole, adminRole);
            }
            /**
             * @dev Grants `role` to `account`.
             *
             * Internal function without access restriction.
             *
             * May emit a {RoleGranted} event.
             */
            function _grantRole(bytes32 role, address account) internal virtual {
                if (!hasRole(role, account)) {
                    _roles[role].members[account] = true;
                    emit RoleGranted(role, account, _msgSender());
                }
            }
            /**
             * @dev Revokes `role` from `account`.
             *
             * Internal function without access restriction.
             *
             * May emit a {RoleRevoked} event.
             */
            function _revokeRole(bytes32 role, address account) internal virtual {
                if (hasRole(role, account)) {
                    _roles[role].members[account] = false;
                    emit RoleRevoked(role, account, _msgSender());
                }
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts (last updated v4.7.0) (utils/Strings.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev String operations.
         */
        library Strings {
            bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
            uint8 private constant _ADDRESS_LENGTH = 20;
            /**
             * @dev Converts a `uint256` to its ASCII `string` decimal representation.
             */
            function toString(uint256 value) internal pure returns (string memory) {
                // Inspired by OraclizeAPI's implementation - MIT licence
                // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
                if (value == 0) {
                    return "0";
                }
                uint256 temp = value;
                uint256 digits;
                while (temp != 0) {
                    digits++;
                    temp /= 10;
                }
                bytes memory buffer = new bytes(digits);
                while (value != 0) {
                    digits -= 1;
                    buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
                    value /= 10;
                }
                return string(buffer);
            }
            /**
             * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
             */
            function toHexString(uint256 value) internal pure returns (string memory) {
                if (value == 0) {
                    return "0x00";
                }
                uint256 temp = value;
                uint256 length = 0;
                while (temp != 0) {
                    length++;
                    temp >>= 8;
                }
                return toHexString(value, length);
            }
            /**
             * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
             */
            function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
                bytes memory buffer = new bytes(2 * length + 2);
                buffer[0] = "0";
                buffer[1] = "x";
                for (uint256 i = 2 * length + 1; i > 1; --i) {
                    buffer[i] = _HEX_SYMBOLS[value & 0xf];
                    value >>= 4;
                }
                require(value == 0, "Strings: hex length insufficient");
                return string(buffer);
            }
            /**
             * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
             */
            function toHexString(address addr) internal pure returns (string memory) {
                return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../tokens/SBT/ISBT.sol";
        interface ILinkableSBT is ISBT {
            function addLinkPrice() external view returns (uint256);
            function addLinkPriceMASA() external view returns (uint256);
            function queryLinkPrice() external view returns (uint256);
            function queryLinkPriceMASA() external view returns (uint256);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/utils/introspection/ERC165.sol";
        import "@openzeppelin/contracts/utils/Context.sol";
        import "@openzeppelin/contracts/utils/Strings.sol";
        import "./ISBT.sol";
        import "./extensions/ISBTMetadata.sol";
        /// @title SBT
        /// @author Masa Finance
        /// @notice Soulbound token is an NFT token that is not transferable.
        contract SBT is Context, ERC165, ISBT, ISBTMetadata {
            using Strings for uint256;
            // Token name
            string private _name;
            // Token symbol
            string private _symbol;
            // Mapping from token ID to owner address
            mapping(uint256 => address) private _owners;
            // Mapping owner address to token count
            mapping(address => uint256) private _balances;
            /**
             * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
             */
            constructor(string memory name_, string memory symbol_) {
                _name = name_;
                _symbol = symbol_;
            }
            /**
             * @dev See {IERC165-supportsInterface}.
             */
            function supportsInterface(bytes4 interfaceId)
                public
                view
                virtual
                override(ERC165, IERC165)
                returns (bool)
            {
                return
                    interfaceId == type(ISBT).interfaceId ||
                    interfaceId == type(ISBTMetadata).interfaceId ||
                    super.supportsInterface(interfaceId);
            }
            /**
             * @dev See {ISBT-balanceOf}.
             */
            function balanceOf(address owner)
                public
                view
                virtual
                override
                returns (uint256)
            {
                require(owner != address(0), "SBT: address zero is not a valid owner");
                return _balances[owner];
            }
            /**
             * @dev See {ISBT-ownerOf}.
             */
            function ownerOf(uint256 tokenId)
                public
                view
                virtual
                override
                returns (address)
            {
                address owner = _owners[tokenId];
                require(owner != address(0), "SBT: invalid token ID");
                return owner;
            }
            /**
             * @dev See {ISBTMetadata-name}.
             */
            function name() public view virtual override returns (string memory) {
                return _name;
            }
            /**
             * @dev See {ISBTMetadata-symbol}.
             */
            function symbol() public view virtual override returns (string memory) {
                return _symbol;
            }
            /**
             * @dev See {ISBTMetadata-tokenURI}.
             */
            function tokenURI(uint256 tokenId)
                public
                view
                virtual
                override
                returns (string memory)
            {
                _requireMinted(tokenId);
                string memory baseURI = _baseURI();
                return
                    bytes(baseURI).length > 0
                        ? string(abi.encodePacked(baseURI, tokenId.toString()))
                        : "";
            }
            /**
             * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
             * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
             * by default, can be overridden in child contracts.
             */
            function _baseURI() internal view virtual returns (string memory) {
                return "";
            }
            /**
             * @dev Returns whether `spender` is allowed to manage `tokenId`.
             *
             * Requirements:
             *
             * - `tokenId` must exist.
             */
            function _isOwner(address spender, uint256 tokenId)
                internal
                view
                virtual
                returns (bool)
            {
                address owner = SBT.ownerOf(tokenId);
                return (spender == owner);
            }
            /**
             * @dev Returns whether `tokenId` exists.
             *
             * Tokens can be managed by their owner.
             *
             * Tokens start existing when they are minted (`_mint`),
             * and stop existing when they are burned (`_burn`).
             */
            function _exists(uint256 tokenId) internal view virtual returns (bool) {
                return _owners[tokenId] != address(0);
            }
            /**
             * @dev Mints `tokenId` and transfers it to `to`.
             *
             * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
             *
             * Requirements:
             *
             * - `tokenId` must not exist.
             * - `to` cannot be the zero address.
             *
             * Emits a {Mint} event.
             */
            function _mint(address to, uint256 tokenId) internal virtual {
                require(to != address(0), "SBT: mint to the zero address");
                require(!_exists(tokenId), "SBT: token already minted");
                _beforeTokenTransfer(address(0), to, tokenId);
                _balances[to] += 1;
                _owners[tokenId] = to;
                emit Mint(to, tokenId);
                _afterTokenTransfer(address(0), to, tokenId);
            }
            /**
             * @dev Destroys `tokenId`.
             *
             * Requirements:
             * - `tokenId` must exist.
             *
             * Emits a {Burn} event.
             */
            function _burn(uint256 tokenId) internal virtual {
                address owner = SBT.ownerOf(tokenId);
                _beforeTokenTransfer(owner, address(0), tokenId);
                _balances[owner] -= 1;
                delete _owners[tokenId];
                emit Burn(owner, tokenId);
                _afterTokenTransfer(owner, address(0), tokenId);
            }
            /**
             * @dev Reverts if the `tokenId` has not been minted yet.
             */
            function _requireMinted(uint256 tokenId) internal view virtual {
                require(_exists(tokenId), "SBT: invalid token ID");
            }
            /**
             * @dev Hook that is called before any token minting/burning
             *
             * Calling conditions:
             *
             * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
             * transferred to `to`.
             * - When `from` is zero, `tokenId` will be minted for `to`.
             * - When `to` is zero, ``from``'s `tokenId` will be burned.
             * - `from` and `to` are never both zero.
             *
             * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
             */
            function _beforeTokenTransfer(
                address,
                address,
                uint256
            ) internal virtual {}
            /**
             * @dev Hook that is called after any minting/burning of tokens
             *
             * Calling conditions:
             * - when `from` and `to` are both non-zero.
             * - `from` and `to` are never both zero.
             *
             * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
             */
            function _afterTokenTransfer(
                address,
                address,
                uint256
            ) internal virtual {}
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../SBT.sol";
        import "./ISBTEnumerable.sol";
        /**
         * @dev This implements an optional extension of {SBT} defined in the EIP that adds
         * enumerability of all the token ids in the contract as well as all token ids owned by each
         * account.
         */
        abstract contract SBTEnumerable is SBT, ISBTEnumerable {
            // Mapping from owner to list of owned token IDs
            mapping(address => mapping(uint256 => uint256)) private _ownedTokens;
            // Mapping from token ID to index of the owner tokens list
            mapping(uint256 => uint256) private _ownedTokensIndex;
            // Array with all token ids, used for enumeration
            uint256[] private _allTokens;
            // Mapping from token id to position in the allTokens array
            mapping(uint256 => uint256) private _allTokensIndex;
            /**
             * @dev See {IERC165-supportsInterface}.
             */
            function supportsInterface(bytes4 interfaceId)
                public
                view
                virtual
                override(IERC165, SBT)
                returns (bool)
            {
                return
                    interfaceId == type(ISBTEnumerable).interfaceId ||
                    super.supportsInterface(interfaceId);
            }
            /**
             * @dev See {ISBTEnumerable-tokenOfOwnerByIndex}.
             */
            function tokenOfOwnerByIndex(address owner, uint256 index)
                public
                view
                virtual
                override
                returns (uint256)
            {
                require(
                    index < SBT.balanceOf(owner),
                    "SBTEnumerable: owner index out of bounds"
                );
                return _ownedTokens[owner][index];
            }
            /**
             * @dev See {ISBTEnumerable-totalSupply}.
             */
            function totalSupply() public view virtual override returns (uint256) {
                return _allTokens.length;
            }
            /**
             * @dev See {ISBTEnumerable-tokenByIndex}.
             */
            function tokenByIndex(uint256 index)
                public
                view
                virtual
                override
                returns (uint256)
            {
                require(
                    index < SBTEnumerable.totalSupply(),
                    "SBTEnumerable: global index out of bounds"
                );
                return _allTokens[index];
            }
            /**
             * @dev Hook that is called before any token transfer. This includes minting
             * and burning.
             *
             * Calling conditions:
             *
             * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
             * transferred to `to`.
             * - When `from` is zero, `tokenId` will be minted for `to`.
             * - When `to` is zero, ``from``'s `tokenId` will be burned.
             * - `from` cannot be the zero address.
             * - `to` cannot be the zero address.
             *
             * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
             */
            function _beforeTokenTransfer(
                address from,
                address to,
                uint256 tokenId
            ) internal virtual override {
                super._beforeTokenTransfer(from, to, tokenId);
                if (from == address(0)) {
                    _addTokenToAllTokensEnumeration(tokenId);
                } else if (from != to) {
                    _removeTokenFromOwnerEnumeration(from, tokenId);
                }
                if (to == address(0)) {
                    _removeTokenFromAllTokensEnumeration(tokenId);
                } else if (to != from) {
                    _addTokenToOwnerEnumeration(to, tokenId);
                }
            }
            /**
             * @dev Private function to add a token to this extension's ownership-tracking data structures.
             * @param to address representing the new owner of the given token ID
             * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
             */
            function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
                uint256 length = SBT.balanceOf(to);
                _ownedTokens[to][length] = tokenId;
                _ownedTokensIndex[tokenId] = length;
            }
            /**
             * @dev Private function to add a token to this extension's token tracking data structures.
             * @param tokenId uint256 ID of the token to be added to the tokens list
             */
            function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
                _allTokensIndex[tokenId] = _allTokens.length;
                _allTokens.push(tokenId);
            }
            /**
             * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
             * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
             * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
             * This has O(1) time complexity, but alters the order of the _ownedTokens array.
             * @param from address representing the previous owner of the given token ID
             * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
             */
            function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId)
                private
            {
                // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
                // then delete the last slot (swap and pop).
                uint256 lastTokenIndex = SBT.balanceOf(from) - 1;
                uint256 tokenIndex = _ownedTokensIndex[tokenId];
                // When the token to delete is the last token, the swap operation is unnecessary
                if (tokenIndex != lastTokenIndex) {
                    uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];
                    _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
                    _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
                }
                // This also deletes the contents at the last position of the array
                delete _ownedTokensIndex[tokenId];
                delete _ownedTokens[from][lastTokenIndex];
            }
            /**
             * @dev Private function to remove a token from this extension's token tracking data structures.
             * This has O(1) time complexity, but alters the order of the _allTokens array.
             * @param tokenId uint256 ID of the token to be removed from the tokens list
             */
            function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
                // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
                // then delete the last slot (swap and pop).
                uint256 lastTokenIndex = _allTokens.length - 1;
                uint256 tokenIndex = _allTokensIndex[tokenId];
                // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
                // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
                // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
                uint256 lastTokenId = _allTokens[lastTokenIndex];
                _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
                _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
                // This also deletes the contents at the last position of the array
                delete _allTokensIndex[tokenId];
                _allTokens.pop();
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "@openzeppelin/contracts/utils/Context.sol";
        import "../SBT.sol";
        /**
         * @title SBT Burnable Token
         * @dev SBT Token that can be burned (destroyed).
         */
        abstract contract SBTBurnable is Context, SBT {
            /**
             * @dev Burns `tokenId`. See {SBT-_burn}.
             *
             * Requirements:
             *
             * - The caller must own `tokenId` or be an approved operator.
             */
            function burn(uint256 tokenId) public virtual {
                //solhint-disable-next-line max-line-length
                require(
                    _isOwner(_msgSender(), tokenId),
                    "SBT: caller is not token owner"
                );
                _burn(tokenId);
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev External interface of AccessControl declared to support ERC165 detection.
         */
        interface IAccessControl {
            /**
             * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
             *
             * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
             * {RoleAdminChanged} not being emitted signaling this.
             *
             * _Available since v3.1._
             */
            event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
            /**
             * @dev Emitted when `account` is granted `role`.
             *
             * `sender` is the account that originated the contract call, an admin role
             * bearer except when using {AccessControl-_setupRole}.
             */
            event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
            /**
             * @dev Emitted when `account` is revoked `role`.
             *
             * `sender` is the account that originated the contract call:
             *   - if using `revokeRole`, it is the admin role bearer
             *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
             */
            event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
            /**
             * @dev Returns `true` if `account` has been granted `role`.
             */
            function hasRole(bytes32 role, address account) external view returns (bool);
            /**
             * @dev Returns the admin role that controls `role`. See {grantRole} and
             * {revokeRole}.
             *
             * To change a role's admin, use {AccessControl-_setRoleAdmin}.
             */
            function getRoleAdmin(bytes32 role) external view returns (bytes32);
            /**
             * @dev Grants `role` to `account`.
             *
             * If `account` had not been already granted `role`, emits a {RoleGranted}
             * event.
             *
             * Requirements:
             *
             * - the caller must have ``role``'s admin role.
             */
            function grantRole(bytes32 role, address account) external;
            /**
             * @dev Revokes `role` from `account`.
             *
             * If `account` had been granted `role`, emits a {RoleRevoked} event.
             *
             * Requirements:
             *
             * - the caller must have ``role``'s admin role.
             */
            function revokeRole(bytes32 role, address account) external;
            /**
             * @dev Revokes `role` from the calling account.
             *
             * Roles are often managed via {grantRole} and {revokeRole}: this function's
             * purpose is to provide a mechanism for accounts to lose their privileges
             * if they are compromised (such as when a trusted device is misplaced).
             *
             * If the calling account had been granted `role`, emits a {RoleRevoked}
             * event.
             *
             * Requirements:
             *
             * - the caller must be `account`.
             */
            function renounceRole(bytes32 role, address account) external;
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
        pragma solidity ^0.8.0;
        /**
         * @dev Provides information about the current execution context, including the
         * sender of the transaction and its data. While these are generally available
         * via msg.sender and msg.data, they should not be accessed in such a direct
         * manner, since when dealing with meta-transactions the account sending and
         * paying for execution may not be the actual sender (as far as an application
         * is concerned).
         *
         * This contract is only required for intermediate, library-like contracts.
         */
        abstract contract Context {
            function _msgSender() internal view virtual returns (address) {
                return msg.sender;
            }
            function _msgData() internal view virtual returns (bytes calldata) {
                return msg.data;
            }
        }
        // SPDX-License-Identifier: MIT
        // OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)
        pragma solidity ^0.8.0;
        import "./IERC165.sol";
        /**
         * @dev Implementation of the {IERC165} interface.
         *
         * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
         * for the additional interface id that will be supported. For example:
         *
         * ```solidity
         * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
         *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
         * }
         * ```
         *
         * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
         */
        abstract contract ERC165 is IERC165 {
            /**
             * @dev See {IERC165-supportsInterface}.
             */
            function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
                return interfaceId == type(IERC165).interfaceId;
            }
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../ISBT.sol";
        /**
         * @title SBT Soulbound Token Standard, optional metadata extension
         */
        interface ISBTMetadata is ISBT {
            /**
             * @dev Returns the token collection name.
             */
            function name() external view returns (string memory);
            /**
             * @dev Returns the token collection symbol.
             */
            function symbol() external view returns (string memory);
            /**
             * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
             */
            function tokenURI(uint256 tokenId) external view returns (string memory);
        }
        // SPDX-License-Identifier: MIT
        pragma solidity ^0.8.7;
        import "../ISBT.sol";
        /**
         * @title SBT Soulbound Token Standard, optional enumeration extension
         */
        interface ISBTEnumerable is ISBT {
            /**
             * @dev Returns the total amount of tokens stored by the contract.
             */
            function totalSupply() external view returns (uint256);
            /**
             * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
             * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
             */
            function tokenOfOwnerByIndex(address owner, uint256 index)
                external
                view
                returns (uint256);
            /**
             * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
             * Use along with {totalSupply} to enumerate all tokens.
             */
            function tokenByIndex(uint256 index) external view returns (uint256);
        }
        

        File 4 of 6: UniswapV2Router02
        pragma solidity =0.6.6;
        
        interface IUniswapV2Factory {
            event PairCreated(address indexed token0, address indexed token1, address pair, uint);
        
            function feeTo() external view returns (address);
            function feeToSetter() external view returns (address);
        
            function getPair(address tokenA, address tokenB) external view returns (address pair);
            function allPairs(uint) external view returns (address pair);
            function allPairsLength() external view returns (uint);
        
            function createPair(address tokenA, address tokenB) external returns (address pair);
        
            function setFeeTo(address) external;
            function setFeeToSetter(address) external;
        }
        
        interface IUniswapV2Pair {
            event Approval(address indexed owner, address indexed spender, uint value);
            event Transfer(address indexed from, address indexed to, uint value);
        
            function name() external pure returns (string memory);
            function symbol() external pure returns (string memory);
            function decimals() external pure returns (uint8);
            function totalSupply() external view returns (uint);
            function balanceOf(address owner) external view returns (uint);
            function allowance(address owner, address spender) external view returns (uint);
        
            function approve(address spender, uint value) external returns (bool);
            function transfer(address to, uint value) external returns (bool);
            function transferFrom(address from, address to, uint value) external returns (bool);
        
            function DOMAIN_SEPARATOR() external view returns (bytes32);
            function PERMIT_TYPEHASH() external pure returns (bytes32);
            function nonces(address owner) external view returns (uint);
        
            function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
        
            event Mint(address indexed sender, uint amount0, uint amount1);
            event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
            event Swap(
                address indexed sender,
                uint amount0In,
                uint amount1In,
                uint amount0Out,
                uint amount1Out,
                address indexed to
            );
            event Sync(uint112 reserve0, uint112 reserve1);
        
            function MINIMUM_LIQUIDITY() external pure returns (uint);
            function factory() external view returns (address);
            function token0() external view returns (address);
            function token1() external view returns (address);
            function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
            function price0CumulativeLast() external view returns (uint);
            function price1CumulativeLast() external view returns (uint);
            function kLast() external view returns (uint);
        
            function mint(address to) external returns (uint liquidity);
            function burn(address to) external returns (uint amount0, uint amount1);
            function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
            function skim(address to) external;
            function sync() external;
        
            function initialize(address, address) external;
        }
        
        interface IUniswapV2Router01 {
            function factory() external pure returns (address);
            function WETH() external pure returns (address);
        
            function addLiquidity(
                address tokenA,
                address tokenB,
                uint amountADesired,
                uint amountBDesired,
                uint amountAMin,
                uint amountBMin,
                address to,
                uint deadline
            ) external returns (uint amountA, uint amountB, uint liquidity);
            function addLiquidityETH(
                address token,
                uint amountTokenDesired,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline
            ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
            function removeLiquidity(
                address tokenA,
                address tokenB,
                uint liquidity,
                uint amountAMin,
                uint amountBMin,
                address to,
                uint deadline
            ) external returns (uint amountA, uint amountB);
            function removeLiquidityETH(
                address token,
                uint liquidity,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline
            ) external returns (uint amountToken, uint amountETH);
            function removeLiquidityWithPermit(
                address tokenA,
                address tokenB,
                uint liquidity,
                uint amountAMin,
                uint amountBMin,
                address to,
                uint deadline,
                bool approveMax, uint8 v, bytes32 r, bytes32 s
            ) external returns (uint amountA, uint amountB);
            function removeLiquidityETHWithPermit(
                address token,
                uint liquidity,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline,
                bool approveMax, uint8 v, bytes32 r, bytes32 s
            ) external returns (uint amountToken, uint amountETH);
            function swapExactTokensForTokens(
                uint amountIn,
                uint amountOutMin,
                address[] calldata path,
                address to,
                uint deadline
            ) external returns (uint[] memory amounts);
            function swapTokensForExactTokens(
                uint amountOut,
                uint amountInMax,
                address[] calldata path,
                address to,
                uint deadline
            ) external returns (uint[] memory amounts);
            function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
                external
                payable
                returns (uint[] memory amounts);
            function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
                external
                returns (uint[] memory amounts);
            function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
                external
                returns (uint[] memory amounts);
            function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
                external
                payable
                returns (uint[] memory amounts);
        
            function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
            function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
            function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
            function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
            function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
        }
        
        interface IUniswapV2Router02 is IUniswapV2Router01 {
            function removeLiquidityETHSupportingFeeOnTransferTokens(
                address token,
                uint liquidity,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline
            ) external returns (uint amountETH);
            function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
                address token,
                uint liquidity,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline,
                bool approveMax, uint8 v, bytes32 r, bytes32 s
            ) external returns (uint amountETH);
        
            function swapExactTokensForTokensSupportingFeeOnTransferTokens(
                uint amountIn,
                uint amountOutMin,
                address[] calldata path,
                address to,
                uint deadline
            ) external;
            function swapExactETHForTokensSupportingFeeOnTransferTokens(
                uint amountOutMin,
                address[] calldata path,
                address to,
                uint deadline
            ) external payable;
            function swapExactTokensForETHSupportingFeeOnTransferTokens(
                uint amountIn,
                uint amountOutMin,
                address[] calldata path,
                address to,
                uint deadline
            ) external;
        }
        
        interface IERC20 {
            event Approval(address indexed owner, address indexed spender, uint value);
            event Transfer(address indexed from, address indexed to, uint value);
        
            function name() external view returns (string memory);
            function symbol() external view returns (string memory);
            function decimals() external view returns (uint8);
            function totalSupply() external view returns (uint);
            function balanceOf(address owner) external view returns (uint);
            function allowance(address owner, address spender) external view returns (uint);
        
            function approve(address spender, uint value) external returns (bool);
            function transfer(address to, uint value) external returns (bool);
            function transferFrom(address from, address to, uint value) external returns (bool);
        }
        
        interface IWETH {
            function deposit() external payable;
            function transfer(address to, uint value) external returns (bool);
            function withdraw(uint) external;
        }
        
        contract UniswapV2Router02 is IUniswapV2Router02 {
            using SafeMath for uint;
        
            address public immutable override factory;
            address public immutable override WETH;
        
            modifier ensure(uint deadline) {
                require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');
                _;
            }
        
            constructor(address _factory, address _WETH) public {
                factory = _factory;
                WETH = _WETH;
            }
        
            receive() external payable {
                assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract
            }
        
            // **** ADD LIQUIDITY ****
            function _addLiquidity(
                address tokenA,
                address tokenB,
                uint amountADesired,
                uint amountBDesired,
                uint amountAMin,
                uint amountBMin
            ) internal virtual returns (uint amountA, uint amountB) {
                // create the pair if it doesn't exist yet
                if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
                    IUniswapV2Factory(factory).createPair(tokenA, tokenB);
                }
                (uint reserveA, uint reserveB) = UniswapV2Library.getReserves(factory, tokenA, tokenB);
                if (reserveA == 0 && reserveB == 0) {
                    (amountA, amountB) = (amountADesired, amountBDesired);
                } else {
                    uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);
                    if (amountBOptimal <= amountBDesired) {
                        require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
                        (amountA, amountB) = (amountADesired, amountBOptimal);
                    } else {
                        uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);
                        assert(amountAOptimal <= amountADesired);
                        require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
                        (amountA, amountB) = (amountAOptimal, amountBDesired);
                    }
                }
            }
            function addLiquidity(
                address tokenA,
                address tokenB,
                uint amountADesired,
                uint amountBDesired,
                uint amountAMin,
                uint amountBMin,
                address to,
                uint deadline
            ) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
                (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
                address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
                TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
                TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
                liquidity = IUniswapV2Pair(pair).mint(to);
            }
            function addLiquidityETH(
                address token,
                uint amountTokenDesired,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline
            ) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {
                (amountToken, amountETH) = _addLiquidity(
                    token,
                    WETH,
                    amountTokenDesired,
                    msg.value,
                    amountTokenMin,
                    amountETHMin
                );
                address pair = UniswapV2Library.pairFor(factory, token, WETH);
                TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
                IWETH(WETH).deposit{value: amountETH}();
                assert(IWETH(WETH).transfer(pair, amountETH));
                liquidity = IUniswapV2Pair(pair).mint(to);
                // refund dust eth, if any
                if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH);
            }
        
            // **** REMOVE LIQUIDITY ****
            function removeLiquidity(
                address tokenA,
                address tokenB,
                uint liquidity,
                uint amountAMin,
                uint amountBMin,
                address to,
                uint deadline
            ) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {
                address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
                IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
                (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);
                (address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);
                (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
                require(amountA >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
                require(amountB >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
            }
            function removeLiquidityETH(
                address token,
                uint liquidity,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline
            ) public virtual override ensure(deadline) returns (uint amountToken, uint amountETH) {
                (amountToken, amountETH) = removeLiquidity(
                    token,
                    WETH,
                    liquidity,
                    amountTokenMin,
                    amountETHMin,
                    address(this),
                    deadline
                );
                TransferHelper.safeTransfer(token, to, amountToken);
                IWETH(WETH).withdraw(amountETH);
                TransferHelper.safeTransferETH(to, amountETH);
            }
            function removeLiquidityWithPermit(
                address tokenA,
                address tokenB,
                uint liquidity,
                uint amountAMin,
                uint amountBMin,
                address to,
                uint deadline,
                bool approveMax, uint8 v, bytes32 r, bytes32 s
            ) external virtual override returns (uint amountA, uint amountB) {
                address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
                uint value = approveMax ? uint(-1) : liquidity;
                IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
                (amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
            }
            function removeLiquidityETHWithPermit(
                address token,
                uint liquidity,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline,
                bool approveMax, uint8 v, bytes32 r, bytes32 s
            ) external virtual override returns (uint amountToken, uint amountETH) {
                address pair = UniswapV2Library.pairFor(factory, token, WETH);
                uint value = approveMax ? uint(-1) : liquidity;
                IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
                (amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);
            }
        
            // **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****
            function removeLiquidityETHSupportingFeeOnTransferTokens(
                address token,
                uint liquidity,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline
            ) public virtual override ensure(deadline) returns (uint amountETH) {
                (, amountETH) = removeLiquidity(
                    token,
                    WETH,
                    liquidity,
                    amountTokenMin,
                    amountETHMin,
                    address(this),
                    deadline
                );
                TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
                IWETH(WETH).withdraw(amountETH);
                TransferHelper.safeTransferETH(to, amountETH);
            }
            function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
                address token,
                uint liquidity,
                uint amountTokenMin,
                uint amountETHMin,
                address to,
                uint deadline,
                bool approveMax, uint8 v, bytes32 r, bytes32 s
            ) external virtual override returns (uint amountETH) {
                address pair = UniswapV2Library.pairFor(factory, token, WETH);
                uint value = approveMax ? uint(-1) : liquidity;
                IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
                amountETH = removeLiquidityETHSupportingFeeOnTransferTokens(
                    token, liquidity, amountTokenMin, amountETHMin, to, deadline
                );
            }
        
            // **** SWAP ****
            // requires the initial amount to have already been sent to the first pair
            function _swap(uint[] memory amounts, address[] memory path, address _to) internal virtual {
                for (uint i; i < path.length - 1; i++) {
                    (address input, address output) = (path[i], path[i + 1]);
                    (address token0,) = UniswapV2Library.sortTokens(input, output);
                    uint amountOut = amounts[i + 1];
                    (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));
                    address to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;
                    IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output)).swap(
                        amount0Out, amount1Out, to, new bytes(0)
                    );
                }
            }
            function swapExactTokensForTokens(
                uint amountIn,
                uint amountOutMin,
                address[] calldata path,
                address to,
                uint deadline
            ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
                amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
                require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
                TransferHelper.safeTransferFrom(
                    path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
                );
                _swap(amounts, path, to);
            }
            function swapTokensForExactTokens(
                uint amountOut,
                uint amountInMax,
                address[] calldata path,
                address to,
                uint deadline
            ) external virtual override ensure(deadline) returns (uint[] memory amounts) {
                amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
                require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
                TransferHelper.safeTransferFrom(
                    path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
                );
                _swap(amounts, path, to);
            }
            function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
                external
                virtual
                override
                payable
                ensure(deadline)
                returns (uint[] memory amounts)
            {
                require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
                amounts = UniswapV2Library.getAmountsOut(factory, msg.value, path);
                require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
                IWETH(WETH).deposit{value: amounts[0]}();
                assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));
                _swap(amounts, path, to);
            }
            function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
                external
                virtual
                override
                ensure(deadline)
                returns (uint[] memory amounts)
            {
                require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
                amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
                require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
                TransferHelper.safeTransferFrom(
                    path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
                );
                _swap(amounts, path, address(this));
                IWETH(WETH).withdraw(amounts[amounts.length - 1]);
                TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
            }
            function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
                external
                virtual
                override
                ensure(deadline)
                returns (uint[] memory amounts)
            {
                require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
                amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
                require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
                TransferHelper.safeTransferFrom(
                    path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]
                );
                _swap(amounts, path, address(this));
                IWETH(WETH).withdraw(amounts[amounts.length - 1]);
                TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
            }
            function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
                external
                virtual
                override
                payable
                ensure(deadline)
                returns (uint[] memory amounts)
            {
                require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
                amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
                require(amounts[0] <= msg.value, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
                IWETH(WETH).deposit{value: amounts[0]}();
                assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));
                _swap(amounts, path, to);
                // refund dust eth, if any
                if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]);
            }
        
            // **** SWAP (supporting fee-on-transfer tokens) ****
            // requires the initial amount to have already been sent to the first pair
            function _swapSupportingFeeOnTransferTokens(address[] memory path, address _to) internal virtual {
                for (uint i; i < path.length - 1; i++) {
                    (address input, address output) = (path[i], path[i + 1]);
                    (address token0,) = UniswapV2Library.sortTokens(input, output);
                    IUniswapV2Pair pair = IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output));
                    uint amountInput;
                    uint amountOutput;
                    { // scope to avoid stack too deep errors
                    (uint reserve0, uint reserve1,) = pair.getReserves();
                    (uint reserveInput, uint reserveOutput) = input == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
                    amountInput = IERC20(input).balanceOf(address(pair)).sub(reserveInput);
                    amountOutput = UniswapV2Library.getAmountOut(amountInput, reserveInput, reserveOutput);
                    }
                    (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOutput) : (amountOutput, uint(0));
                    address to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;
                    pair.swap(amount0Out, amount1Out, to, new bytes(0));
                }
            }
            function swapExactTokensForTokensSupportingFeeOnTransferTokens(
                uint amountIn,
                uint amountOutMin,
                address[] calldata path,
                address to,
                uint deadline
            ) external virtual override ensure(deadline) {
                TransferHelper.safeTransferFrom(
                    path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn
                );
                uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
                _swapSupportingFeeOnTransferTokens(path, to);
                require(
                    IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
                    'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'
                );
            }
            function swapExactETHForTokensSupportingFeeOnTransferTokens(
                uint amountOutMin,
                address[] calldata path,
                address to,
                uint deadline
            )
                external
                virtual
                override
                payable
                ensure(deadline)
            {
                require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
                uint amountIn = msg.value;
                IWETH(WETH).deposit{value: amountIn}();
                assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn));
                uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
                _swapSupportingFeeOnTransferTokens(path, to);
                require(
                    IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
                    'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'
                );
            }
            function swapExactTokensForETHSupportingFeeOnTransferTokens(
                uint amountIn,
                uint amountOutMin,
                address[] calldata path,
                address to,
                uint deadline
            )
                external
                virtual
                override
                ensure(deadline)
            {
                require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
                TransferHelper.safeTransferFrom(
                    path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amountIn
                );
                _swapSupportingFeeOnTransferTokens(path, address(this));
                uint amountOut = IERC20(WETH).balanceOf(address(this));
                require(amountOut >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
                IWETH(WETH).withdraw(amountOut);
                TransferHelper.safeTransferETH(to, amountOut);
            }
        
            // **** LIBRARY FUNCTIONS ****
            function quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {
                return UniswapV2Library.quote(amountA, reserveA, reserveB);
            }
        
            function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)
                public
                pure
                virtual
                override
                returns (uint amountOut)
            {
                return UniswapV2Library.getAmountOut(amountIn, reserveIn, reserveOut);
            }
        
            function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)
                public
                pure
                virtual
                override
                returns (uint amountIn)
            {
                return UniswapV2Library.getAmountIn(amountOut, reserveIn, reserveOut);
            }
        
            function getAmountsOut(uint amountIn, address[] memory path)
                public
                view
                virtual
                override
                returns (uint[] memory amounts)
            {
                return UniswapV2Library.getAmountsOut(factory, amountIn, path);
            }
        
            function getAmountsIn(uint amountOut, address[] memory path)
                public
                view
                virtual
                override
                returns (uint[] memory amounts)
            {
                return UniswapV2Library.getAmountsIn(factory, amountOut, path);
            }
        }
        
        // a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)
        
        library SafeMath {
            function add(uint x, uint y) internal pure returns (uint z) {
                require((z = x + y) >= x, 'ds-math-add-overflow');
            }
        
            function sub(uint x, uint y) internal pure returns (uint z) {
                require((z = x - y) <= x, 'ds-math-sub-underflow');
            }
        
            function mul(uint x, uint y) internal pure returns (uint z) {
                require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
            }
        }
        
        library UniswapV2Library {
            using SafeMath for uint;
        
            // returns sorted token addresses, used to handle return values from pairs sorted in this order
            function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
                require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
                (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
                require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
            }
        
            // calculates the CREATE2 address for a pair without making any external calls
            function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
                (address token0, address token1) = sortTokens(tokenA, tokenB);
                pair = address(uint(keccak256(abi.encodePacked(
                        hex'ff',
                        factory,
                        keccak256(abi.encodePacked(token0, token1)),
                        hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
                    ))));
            }
        
            // fetches and sorts the reserves for a pair
            function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
                (address token0,) = sortTokens(tokenA, tokenB);
                (uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
                (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
            }
        
            // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
            function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
                require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
                require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
                amountB = amountA.mul(reserveB) / reserveA;
            }
        
            // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
            function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {
                require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
                require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
                uint amountInWithFee = amountIn.mul(997);
                uint numerator = amountInWithFee.mul(reserveOut);
                uint denominator = reserveIn.mul(1000).add(amountInWithFee);
                amountOut = numerator / denominator;
            }
        
            // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
            function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {
                require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
                require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
                uint numerator = reserveIn.mul(amountOut).mul(1000);
                uint denominator = reserveOut.sub(amountOut).mul(997);
                amountIn = (numerator / denominator).add(1);
            }
        
            // performs chained getAmountOut calculations on any number of pairs
            function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {
                require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
                amounts = new uint[](path.length);
                amounts[0] = amountIn;
                for (uint i; i < path.length - 1; i++) {
                    (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);
                    amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
                }
            }
        
            // performs chained getAmountIn calculations on any number of pairs
            function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {
                require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
                amounts = new uint[](path.length);
                amounts[amounts.length - 1] = amountOut;
                for (uint i = path.length - 1; i > 0; i--) {
                    (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);
                    amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
                }
            }
        }
        
        // helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
        library TransferHelper {
            function safeApprove(address token, address to, uint value) internal {
                // bytes4(keccak256(bytes('approve(address,uint256)')));
                (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
                require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
            }
        
            function safeTransfer(address token, address to, uint value) internal {
                // bytes4(keccak256(bytes('transfer(address,uint256)')));
                (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
                require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
            }
        
            function safeTransferFrom(address token, address from, address to, uint value) internal {
                // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
                (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
                require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
            }
        
            function safeTransferETH(address to, uint value) internal {
                (bool success,) = to.call{value:value}(new bytes(0));
                require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
            }
        }

        File 5 of 6: UniswapV2Pair
        // File: contracts/interfaces/IUniswapV2Pair.sol
        
        pragma solidity >=0.5.0;
        
        interface IUniswapV2Pair {
            event Approval(address indexed owner, address indexed spender, uint value);
            event Transfer(address indexed from, address indexed to, uint value);
        
            function name() external pure returns (string memory);
            function symbol() external pure returns (string memory);
            function decimals() external pure returns (uint8);
            function totalSupply() external view returns (uint);
            function balanceOf(address owner) external view returns (uint);
            function allowance(address owner, address spender) external view returns (uint);
        
            function approve(address spender, uint value) external returns (bool);
            function transfer(address to, uint value) external returns (bool);
            function transferFrom(address from, address to, uint value) external returns (bool);
        
            function DOMAIN_SEPARATOR() external view returns (bytes32);
            function PERMIT_TYPEHASH() external pure returns (bytes32);
            function nonces(address owner) external view returns (uint);
        
            function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
        
            event Mint(address indexed sender, uint amount0, uint amount1);
            event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
            event Swap(
                address indexed sender,
                uint amount0In,
                uint amount1In,
                uint amount0Out,
                uint amount1Out,
                address indexed to
            );
            event Sync(uint112 reserve0, uint112 reserve1);
        
            function MINIMUM_LIQUIDITY() external pure returns (uint);
            function factory() external view returns (address);
            function token0() external view returns (address);
            function token1() external view returns (address);
            function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
            function price0CumulativeLast() external view returns (uint);
            function price1CumulativeLast() external view returns (uint);
            function kLast() external view returns (uint);
        
            function mint(address to) external returns (uint liquidity);
            function burn(address to) external returns (uint amount0, uint amount1);
            function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
            function skim(address to) external;
            function sync() external;
        
            function initialize(address, address) external;
        }
        
        // File: contracts/interfaces/IUniswapV2ERC20.sol
        
        pragma solidity >=0.5.0;
        
        interface IUniswapV2ERC20 {
            event Approval(address indexed owner, address indexed spender, uint value);
            event Transfer(address indexed from, address indexed to, uint value);
        
            function name() external pure returns (string memory);
            function symbol() external pure returns (string memory);
            function decimals() external pure returns (uint8);
            function totalSupply() external view returns (uint);
            function balanceOf(address owner) external view returns (uint);
            function allowance(address owner, address spender) external view returns (uint);
        
            function approve(address spender, uint value) external returns (bool);
            function transfer(address to, uint value) external returns (bool);
            function transferFrom(address from, address to, uint value) external returns (bool);
        
            function DOMAIN_SEPARATOR() external view returns (bytes32);
            function PERMIT_TYPEHASH() external pure returns (bytes32);
            function nonces(address owner) external view returns (uint);
        
            function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
        }
        
        // File: contracts/libraries/SafeMath.sol
        
        pragma solidity =0.5.16;
        
        // a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)
        
        library SafeMath {
            function add(uint x, uint y) internal pure returns (uint z) {
                require((z = x + y) >= x, 'ds-math-add-overflow');
            }
        
            function sub(uint x, uint y) internal pure returns (uint z) {
                require((z = x - y) <= x, 'ds-math-sub-underflow');
            }
        
            function mul(uint x, uint y) internal pure returns (uint z) {
                require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
            }
        }
        
        // File: contracts/UniswapV2ERC20.sol
        
        pragma solidity =0.5.16;
        
        
        
        contract UniswapV2ERC20 is IUniswapV2ERC20 {
            using SafeMath for uint;
        
            string public constant name = 'Uniswap V2';
            string public constant symbol = 'UNI-V2';
            uint8 public constant decimals = 18;
            uint  public totalSupply;
            mapping(address => uint) public balanceOf;
            mapping(address => mapping(address => uint)) public allowance;
        
            bytes32 public DOMAIN_SEPARATOR;
            // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
            bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
            mapping(address => uint) public nonces;
        
            event Approval(address indexed owner, address indexed spender, uint value);
            event Transfer(address indexed from, address indexed to, uint value);
        
            constructor() public {
                uint chainId;
                assembly {
                    chainId := chainid
                }
                DOMAIN_SEPARATOR = keccak256(
                    abi.encode(
                        keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                        keccak256(bytes(name)),
                        keccak256(bytes('1')),
                        chainId,
                        address(this)
                    )
                );
            }
        
            function _mint(address to, uint value) internal {
                totalSupply = totalSupply.add(value);
                balanceOf[to] = balanceOf[to].add(value);
                emit Transfer(address(0), to, value);
            }
        
            function _burn(address from, uint value) internal {
                balanceOf[from] = balanceOf[from].sub(value);
                totalSupply = totalSupply.sub(value);
                emit Transfer(from, address(0), value);
            }
        
            function _approve(address owner, address spender, uint value) private {
                allowance[owner][spender] = value;
                emit Approval(owner, spender, value);
            }
        
            function _transfer(address from, address to, uint value) private {
                balanceOf[from] = balanceOf[from].sub(value);
                balanceOf[to] = balanceOf[to].add(value);
                emit Transfer(from, to, value);
            }
        
            function approve(address spender, uint value) external returns (bool) {
                _approve(msg.sender, spender, value);
                return true;
            }
        
            function transfer(address to, uint value) external returns (bool) {
                _transfer(msg.sender, to, value);
                return true;
            }
        
            function transferFrom(address from, address to, uint value) external returns (bool) {
                if (allowance[from][msg.sender] != uint(-1)) {
                    allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
                }
                _transfer(from, to, value);
                return true;
            }
        
            function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
                require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
                bytes32 digest = keccak256(
                    abi.encodePacked(
                        '\x19\x01',
                        DOMAIN_SEPARATOR,
                        keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
                    )
                );
                address recoveredAddress = ecrecover(digest, v, r, s);
                require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
                _approve(owner, spender, value);
            }
        }
        
        // File: contracts/libraries/Math.sol
        
        pragma solidity =0.5.16;
        
        // a library for performing various math operations
        
        library Math {
            function min(uint x, uint y) internal pure returns (uint z) {
                z = x < y ? x : y;
            }
        
            // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
            function sqrt(uint y) internal pure returns (uint z) {
                if (y > 3) {
                    z = y;
                    uint x = y / 2 + 1;
                    while (x < z) {
                        z = x;
                        x = (y / x + x) / 2;
                    }
                } else if (y != 0) {
                    z = 1;
                }
            }
        }
        
        // File: contracts/libraries/UQ112x112.sol
        
        pragma solidity =0.5.16;
        
        // a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
        
        // range: [0, 2**112 - 1]
        // resolution: 1 / 2**112
        
        library UQ112x112 {
            uint224 constant Q112 = 2**112;
        
            // encode a uint112 as a UQ112x112
            function encode(uint112 y) internal pure returns (uint224 z) {
                z = uint224(y) * Q112; // never overflows
            }
        
            // divide a UQ112x112 by a uint112, returning a UQ112x112
            function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
                z = x / uint224(y);
            }
        }
        
        // File: contracts/interfaces/IERC20.sol
        
        pragma solidity >=0.5.0;
        
        interface IERC20 {
            event Approval(address indexed owner, address indexed spender, uint value);
            event Transfer(address indexed from, address indexed to, uint value);
        
            function name() external view returns (string memory);
            function symbol() external view returns (string memory);
            function decimals() external view returns (uint8);
            function totalSupply() external view returns (uint);
            function balanceOf(address owner) external view returns (uint);
            function allowance(address owner, address spender) external view returns (uint);
        
            function approve(address spender, uint value) external returns (bool);
            function transfer(address to, uint value) external returns (bool);
            function transferFrom(address from, address to, uint value) external returns (bool);
        }
        
        // File: contracts/interfaces/IUniswapV2Factory.sol
        
        pragma solidity >=0.5.0;
        
        interface IUniswapV2Factory {
            event PairCreated(address indexed token0, address indexed token1, address pair, uint);
        
            function feeTo() external view returns (address);
            function feeToSetter() external view returns (address);
        
            function getPair(address tokenA, address tokenB) external view returns (address pair);
            function allPairs(uint) external view returns (address pair);
            function allPairsLength() external view returns (uint);
        
            function createPair(address tokenA, address tokenB) external returns (address pair);
        
            function setFeeTo(address) external;
            function setFeeToSetter(address) external;
        }
        
        // File: contracts/interfaces/IUniswapV2Callee.sol
        
        pragma solidity >=0.5.0;
        
        interface IUniswapV2Callee {
            function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
        }
        
        // File: contracts/UniswapV2Pair.sol
        
        pragma solidity =0.5.16;
        
        
        
        
        
        
        
        
        contract UniswapV2Pair is IUniswapV2Pair, UniswapV2ERC20 {
            using SafeMath  for uint;
            using UQ112x112 for uint224;
        
            uint public constant MINIMUM_LIQUIDITY = 10**3;
            bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));
        
            address public factory;
            address public token0;
            address public token1;
        
            uint112 private reserve0;           // uses single storage slot, accessible via getReserves
            uint112 private reserve1;           // uses single storage slot, accessible via getReserves
            uint32  private blockTimestampLast; // uses single storage slot, accessible via getReserves
        
            uint public price0CumulativeLast;
            uint public price1CumulativeLast;
            uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event
        
            uint private unlocked = 1;
            modifier lock() {
                require(unlocked == 1, 'UniswapV2: LOCKED');
                unlocked = 0;
                _;
                unlocked = 1;
            }
        
            function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
                _reserve0 = reserve0;
                _reserve1 = reserve1;
                _blockTimestampLast = blockTimestampLast;
            }
        
            function _safeTransfer(address token, address to, uint value) private {
                (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
                require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
            }
        
            event Mint(address indexed sender, uint amount0, uint amount1);
            event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
            event Swap(
                address indexed sender,
                uint amount0In,
                uint amount1In,
                uint amount0Out,
                uint amount1Out,
                address indexed to
            );
            event Sync(uint112 reserve0, uint112 reserve1);
        
            constructor() public {
                factory = msg.sender;
            }
        
            // called once by the factory at time of deployment
            function initialize(address _token0, address _token1) external {
                require(msg.sender == factory, 'UniswapV2: FORBIDDEN'); // sufficient check
                token0 = _token0;
                token1 = _token1;
            }
        
            // update reserves and, on the first call per block, price accumulators
            function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
                require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
                uint32 blockTimestamp = uint32(block.timestamp % 2**32);
                uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
                if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
                    // * never overflows, and + overflow is desired
                    price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
                    price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
                }
                reserve0 = uint112(balance0);
                reserve1 = uint112(balance1);
                blockTimestampLast = blockTimestamp;
                emit Sync(reserve0, reserve1);
            }
        
            // if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k)
            function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
                address feeTo = IUniswapV2Factory(factory).feeTo();
                feeOn = feeTo != address(0);
                uint _kLast = kLast; // gas savings
                if (feeOn) {
                    if (_kLast != 0) {
                        uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
                        uint rootKLast = Math.sqrt(_kLast);
                        if (rootK > rootKLast) {
                            uint numerator = totalSupply.mul(rootK.sub(rootKLast));
                            uint denominator = rootK.mul(5).add(rootKLast);
                            uint liquidity = numerator / denominator;
                            if (liquidity > 0) _mint(feeTo, liquidity);
                        }
                    }
                } else if (_kLast != 0) {
                    kLast = 0;
                }
            }
        
            // this low-level function should be called from a contract which performs important safety checks
            function mint(address to) external lock returns (uint liquidity) {
                (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
                uint balance0 = IERC20(token0).balanceOf(address(this));
                uint balance1 = IERC20(token1).balanceOf(address(this));
                uint amount0 = balance0.sub(_reserve0);
                uint amount1 = balance1.sub(_reserve1);
        
                bool feeOn = _mintFee(_reserve0, _reserve1);
                uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
                if (_totalSupply == 0) {
                    liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
                   _mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
                } else {
                    liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
                }
                require(liquidity > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
                _mint(to, liquidity);
        
                _update(balance0, balance1, _reserve0, _reserve1);
                if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
                emit Mint(msg.sender, amount0, amount1);
            }
        
            // this low-level function should be called from a contract which performs important safety checks
            function burn(address to) external lock returns (uint amount0, uint amount1) {
                (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
                address _token0 = token0;                                // gas savings
                address _token1 = token1;                                // gas savings
                uint balance0 = IERC20(_token0).balanceOf(address(this));
                uint balance1 = IERC20(_token1).balanceOf(address(this));
                uint liquidity = balanceOf[address(this)];
        
                bool feeOn = _mintFee(_reserve0, _reserve1);
                uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
                amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
                amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
                require(amount0 > 0 && amount1 > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_BURNED');
                _burn(address(this), liquidity);
                _safeTransfer(_token0, to, amount0);
                _safeTransfer(_token1, to, amount1);
                balance0 = IERC20(_token0).balanceOf(address(this));
                balance1 = IERC20(_token1).balanceOf(address(this));
        
                _update(balance0, balance1, _reserve0, _reserve1);
                if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
                emit Burn(msg.sender, amount0, amount1, to);
            }
        
            // this low-level function should be called from a contract which performs important safety checks
            function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
                require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
                (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
                require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');
        
                uint balance0;
                uint balance1;
                { // scope for _token{0,1}, avoids stack too deep errors
                address _token0 = token0;
                address _token1 = token1;
                require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
                if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
                if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
                if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
                balance0 = IERC20(_token0).balanceOf(address(this));
                balance1 = IERC20(_token1).balanceOf(address(this));
                }
                uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
                uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
                require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
                { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
                uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
                uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
                require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
                }
        
                _update(balance0, balance1, _reserve0, _reserve1);
                emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
            }
        
            // force balances to match reserves
            function skim(address to) external lock {
                address _token0 = token0; // gas savings
                address _token1 = token1; // gas savings
                _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
                _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
            }
        
            // force reserves to match balances
            function sync() external lock {
                _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
            }
        }

        File 6 of 6: GnosisSafe
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "./base/ModuleManager.sol";
        import "./base/OwnerManager.sol";
        import "./base/FallbackManager.sol";
        import "./base/GuardManager.sol";
        import "./common/EtherPaymentFallback.sol";
        import "./common/Singleton.sol";
        import "./common/SignatureDecoder.sol";
        import "./common/SecuredTokenTransfer.sol";
        import "./common/StorageAccessible.sol";
        import "./interfaces/ISignatureValidator.sol";
        import "./external/GnosisSafeMath.sol";
        /// @title Gnosis Safe - A multisignature wallet with support for confirmations using signed messages based on ERC191.
        /// @author Stefan George - <[email protected]>
        /// @author Richard Meissner - <[email protected]>
        contract GnosisSafe is
            EtherPaymentFallback,
            Singleton,
            ModuleManager,
            OwnerManager,
            SignatureDecoder,
            SecuredTokenTransfer,
            ISignatureValidatorConstants,
            FallbackManager,
            StorageAccessible,
            GuardManager
        {
            using GnosisSafeMath for uint256;
            string public constant VERSION = "1.3.0";
            // keccak256(
            //     "EIP712Domain(uint256 chainId,address verifyingContract)"
            // );
            bytes32 private constant DOMAIN_SEPARATOR_TYPEHASH = 0x47e79534a245952e8b16893a336b85a3d9ea9fa8c573f3d803afb92a79469218;
            // keccak256(
            //     "SafeTx(address to,uint256 value,bytes data,uint8 operation,uint256 safeTxGas,uint256 baseGas,uint256 gasPrice,address gasToken,address refundReceiver,uint256 nonce)"
            // );
            bytes32 private constant SAFE_TX_TYPEHASH = 0xbb8310d486368db6bd6f849402fdd73ad53d316b5a4b2644ad6efe0f941286d8;
            event SafeSetup(address indexed initiator, address[] owners, uint256 threshold, address initializer, address fallbackHandler);
            event ApproveHash(bytes32 indexed approvedHash, address indexed owner);
            event SignMsg(bytes32 indexed msgHash);
            event ExecutionFailure(bytes32 txHash, uint256 payment);
            event ExecutionSuccess(bytes32 txHash, uint256 payment);
            uint256 public nonce;
            bytes32 private _deprecatedDomainSeparator;
            // Mapping to keep track of all message hashes that have been approve by ALL REQUIRED owners
            mapping(bytes32 => uint256) public signedMessages;
            // Mapping to keep track of all hashes (message or transaction) that have been approve by ANY owners
            mapping(address => mapping(bytes32 => uint256)) public approvedHashes;
            // This constructor ensures that this contract can only be used as a master copy for Proxy contracts
            constructor() {
                // By setting the threshold it is not possible to call setup anymore,
                // so we create a Safe with 0 owners and threshold 1.
                // This is an unusable Safe, perfect for the singleton
                threshold = 1;
            }
            /// @dev Setup function sets initial storage of contract.
            /// @param _owners List of Safe owners.
            /// @param _threshold Number of required confirmations for a Safe transaction.
            /// @param to Contract address for optional delegate call.
            /// @param data Data payload for optional delegate call.
            /// @param fallbackHandler Handler for fallback calls to this contract
            /// @param paymentToken Token that should be used for the payment (0 is ETH)
            /// @param payment Value that should be paid
            /// @param paymentReceiver Adddress that should receive the payment (or 0 if tx.origin)
            function setup(
                address[] calldata _owners,
                uint256 _threshold,
                address to,
                bytes calldata data,
                address fallbackHandler,
                address paymentToken,
                uint256 payment,
                address payable paymentReceiver
            ) external {
                // setupOwners checks if the Threshold is already set, therefore preventing that this method is called twice
                setupOwners(_owners, _threshold);
                if (fallbackHandler != address(0)) internalSetFallbackHandler(fallbackHandler);
                // As setupOwners can only be called if the contract has not been initialized we don't need a check for setupModules
                setupModules(to, data);
                if (payment > 0) {
                    // To avoid running into issues with EIP-170 we reuse the handlePayment function (to avoid adjusting code of that has been verified we do not adjust the method itself)
                    // baseGas = 0, gasPrice = 1 and gas = payment => amount = (payment + 0) * 1 = payment
                    handlePayment(payment, 0, 1, paymentToken, paymentReceiver);
                }
                emit SafeSetup(msg.sender, _owners, _threshold, to, fallbackHandler);
            }
            /// @dev Allows to execute a Safe transaction confirmed by required number of owners and then pays the account that submitted the transaction.
            ///      Note: The fees are always transferred, even if the user transaction fails.
            /// @param to Destination address of Safe transaction.
            /// @param value Ether value of Safe transaction.
            /// @param data Data payload of Safe transaction.
            /// @param operation Operation type of Safe transaction.
            /// @param safeTxGas Gas that should be used for the Safe transaction.
            /// @param baseGas Gas costs that are independent of the transaction execution(e.g. base transaction fee, signature check, payment of the refund)
            /// @param gasPrice Gas price that should be used for the payment calculation.
            /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
            /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
            /// @param signatures Packed signature data ({bytes32 r}{bytes32 s}{uint8 v})
            function execTransaction(
                address to,
                uint256 value,
                bytes calldata data,
                Enum.Operation operation,
                uint256 safeTxGas,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address payable refundReceiver,
                bytes memory signatures
            ) public payable virtual returns (bool success) {
                bytes32 txHash;
                // Use scope here to limit variable lifetime and prevent `stack too deep` errors
                {
                    bytes memory txHashData =
                        encodeTransactionData(
                            // Transaction info
                            to,
                            value,
                            data,
                            operation,
                            safeTxGas,
                            // Payment info
                            baseGas,
                            gasPrice,
                            gasToken,
                            refundReceiver,
                            // Signature info
                            nonce
                        );
                    // Increase nonce and execute transaction.
                    nonce++;
                    txHash = keccak256(txHashData);
                    checkSignatures(txHash, txHashData, signatures);
                }
                address guard = getGuard();
                {
                    if (guard != address(0)) {
                        Guard(guard).checkTransaction(
                            // Transaction info
                            to,
                            value,
                            data,
                            operation,
                            safeTxGas,
                            // Payment info
                            baseGas,
                            gasPrice,
                            gasToken,
                            refundReceiver,
                            // Signature info
                            signatures,
                            msg.sender
                        );
                    }
                }
                // We require some gas to emit the events (at least 2500) after the execution and some to perform code until the execution (500)
                // We also include the 1/64 in the check that is not send along with a call to counteract potential shortings because of EIP-150
                require(gasleft() >= ((safeTxGas * 64) / 63).max(safeTxGas + 2500) + 500, "GS010");
                // Use scope here to limit variable lifetime and prevent `stack too deep` errors
                {
                    uint256 gasUsed = gasleft();
                    // If the gasPrice is 0 we assume that nearly all available gas can be used (it is always more than safeTxGas)
                    // We only substract 2500 (compared to the 3000 before) to ensure that the amount passed is still higher than safeTxGas
                    success = execute(to, value, data, operation, gasPrice == 0 ? (gasleft() - 2500) : safeTxGas);
                    gasUsed = gasUsed.sub(gasleft());
                    // If no safeTxGas and no gasPrice was set (e.g. both are 0), then the internal tx is required to be successful
                    // This makes it possible to use `estimateGas` without issues, as it searches for the minimum gas where the tx doesn't revert
                    require(success || safeTxGas != 0 || gasPrice != 0, "GS013");
                    // We transfer the calculated tx costs to the tx.origin to avoid sending it to intermediate contracts that have made calls
                    uint256 payment = 0;
                    if (gasPrice > 0) {
                        payment = handlePayment(gasUsed, baseGas, gasPrice, gasToken, refundReceiver);
                    }
                    if (success) emit ExecutionSuccess(txHash, payment);
                    else emit ExecutionFailure(txHash, payment);
                }
                {
                    if (guard != address(0)) {
                        Guard(guard).checkAfterExecution(txHash, success);
                    }
                }
            }
            function handlePayment(
                uint256 gasUsed,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address payable refundReceiver
            ) private returns (uint256 payment) {
                // solhint-disable-next-line avoid-tx-origin
                address payable receiver = refundReceiver == address(0) ? payable(tx.origin) : refundReceiver;
                if (gasToken == address(0)) {
                    // For ETH we will only adjust the gas price to not be higher than the actual used gas price
                    payment = gasUsed.add(baseGas).mul(gasPrice < tx.gasprice ? gasPrice : tx.gasprice);
                    require(receiver.send(payment), "GS011");
                } else {
                    payment = gasUsed.add(baseGas).mul(gasPrice);
                    require(transferToken(gasToken, receiver, payment), "GS012");
                }
            }
            /**
             * @dev Checks whether the signature provided is valid for the provided data, hash. Will revert otherwise.
             * @param dataHash Hash of the data (could be either a message hash or transaction hash)
             * @param data That should be signed (this is passed to an external validator contract)
             * @param signatures Signature data that should be verified. Can be ECDSA signature, contract signature (EIP-1271) or approved hash.
             */
            function checkSignatures(
                bytes32 dataHash,
                bytes memory data,
                bytes memory signatures
            ) public view {
                // Load threshold to avoid multiple storage loads
                uint256 _threshold = threshold;
                // Check that a threshold is set
                require(_threshold > 0, "GS001");
                checkNSignatures(dataHash, data, signatures, _threshold);
            }
            /**
             * @dev Checks whether the signature provided is valid for the provided data, hash. Will revert otherwise.
             * @param dataHash Hash of the data (could be either a message hash or transaction hash)
             * @param data That should be signed (this is passed to an external validator contract)
             * @param signatures Signature data that should be verified. Can be ECDSA signature, contract signature (EIP-1271) or approved hash.
             * @param requiredSignatures Amount of required valid signatures.
             */
            function checkNSignatures(
                bytes32 dataHash,
                bytes memory data,
                bytes memory signatures,
                uint256 requiredSignatures
            ) public view {
                // Check that the provided signature data is not too short
                require(signatures.length >= requiredSignatures.mul(65), "GS020");
                // There cannot be an owner with address 0.
                address lastOwner = address(0);
                address currentOwner;
                uint8 v;
                bytes32 r;
                bytes32 s;
                uint256 i;
                for (i = 0; i < requiredSignatures; i++) {
                    (v, r, s) = signatureSplit(signatures, i);
                    if (v == 0) {
                        // If v is 0 then it is a contract signature
                        // When handling contract signatures the address of the contract is encoded into r
                        currentOwner = address(uint160(uint256(r)));
                        // Check that signature data pointer (s) is not pointing inside the static part of the signatures bytes
                        // This check is not completely accurate, since it is possible that more signatures than the threshold are send.
                        // Here we only check that the pointer is not pointing inside the part that is being processed
                        require(uint256(s) >= requiredSignatures.mul(65), "GS021");
                        // Check that signature data pointer (s) is in bounds (points to the length of data -> 32 bytes)
                        require(uint256(s).add(32) <= signatures.length, "GS022");
                        // Check if the contract signature is in bounds: start of data is s + 32 and end is start + signature length
                        uint256 contractSignatureLen;
                        // solhint-disable-next-line no-inline-assembly
                        assembly {
                            contractSignatureLen := mload(add(add(signatures, s), 0x20))
                        }
                        require(uint256(s).add(32).add(contractSignatureLen) <= signatures.length, "GS023");
                        // Check signature
                        bytes memory contractSignature;
                        // solhint-disable-next-line no-inline-assembly
                        assembly {
                            // The signature data for contract signatures is appended to the concatenated signatures and the offset is stored in s
                            contractSignature := add(add(signatures, s), 0x20)
                        }
                        require(ISignatureValidator(currentOwner).isValidSignature(data, contractSignature) == EIP1271_MAGIC_VALUE, "GS024");
                    } else if (v == 1) {
                        // If v is 1 then it is an approved hash
                        // When handling approved hashes the address of the approver is encoded into r
                        currentOwner = address(uint160(uint256(r)));
                        // Hashes are automatically approved by the sender of the message or when they have been pre-approved via a separate transaction
                        require(msg.sender == currentOwner || approvedHashes[currentOwner][dataHash] != 0, "GS025");
                    } else if (v > 30) {
                        // If v > 30 then default va (27,28) has been adjusted for eth_sign flow
                        // To support eth_sign and similar we adjust v and hash the messageHash with the Ethereum message prefix before applying ecrecover
                        currentOwner = ecrecover(keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
        32", dataHash)), v - 4, r, s);
                    } else {
                        // Default is the ecrecover flow with the provided data hash
                        // Use ecrecover with the messageHash for EOA signatures
                        currentOwner = ecrecover(dataHash, v, r, s);
                    }
                    require(currentOwner > lastOwner && owners[currentOwner] != address(0) && currentOwner != SENTINEL_OWNERS, "GS026");
                    lastOwner = currentOwner;
                }
            }
            /// @dev Allows to estimate a Safe transaction.
            ///      This method is only meant for estimation purpose, therefore the call will always revert and encode the result in the revert data.
            ///      Since the `estimateGas` function includes refunds, call this method to get an estimated of the costs that are deducted from the safe with `execTransaction`
            /// @param to Destination address of Safe transaction.
            /// @param value Ether value of Safe transaction.
            /// @param data Data payload of Safe transaction.
            /// @param operation Operation type of Safe transaction.
            /// @return Estimate without refunds and overhead fees (base transaction and payload data gas costs).
            /// @notice Deprecated in favor of common/StorageAccessible.sol and will be removed in next version.
            function requiredTxGas(
                address to,
                uint256 value,
                bytes calldata data,
                Enum.Operation operation
            ) external returns (uint256) {
                uint256 startGas = gasleft();
                // We don't provide an error message here, as we use it to return the estimate
                require(execute(to, value, data, operation, gasleft()));
                uint256 requiredGas = startGas - gasleft();
                // Convert response to string and return via error message
                revert(string(abi.encodePacked(requiredGas)));
            }
            /**
             * @dev Marks a hash as approved. This can be used to validate a hash that is used by a signature.
             * @param hashToApprove The hash that should be marked as approved for signatures that are verified by this contract.
             */
            function approveHash(bytes32 hashToApprove) external {
                require(owners[msg.sender] != address(0), "GS030");
                approvedHashes[msg.sender][hashToApprove] = 1;
                emit ApproveHash(hashToApprove, msg.sender);
            }
            /// @dev Returns the chain id used by this contract.
            function getChainId() public view returns (uint256) {
                uint256 id;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    id := chainid()
                }
                return id;
            }
            function domainSeparator() public view returns (bytes32) {
                return keccak256(abi.encode(DOMAIN_SEPARATOR_TYPEHASH, getChainId(), this));
            }
            /// @dev Returns the bytes that are hashed to be signed by owners.
            /// @param to Destination address.
            /// @param value Ether value.
            /// @param data Data payload.
            /// @param operation Operation type.
            /// @param safeTxGas Gas that should be used for the safe transaction.
            /// @param baseGas Gas costs for that are independent of the transaction execution(e.g. base transaction fee, signature check, payment of the refund)
            /// @param gasPrice Maximum gas price that should be used for this transaction.
            /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
            /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
            /// @param _nonce Transaction nonce.
            /// @return Transaction hash bytes.
            function encodeTransactionData(
                address to,
                uint256 value,
                bytes calldata data,
                Enum.Operation operation,
                uint256 safeTxGas,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address refundReceiver,
                uint256 _nonce
            ) public view returns (bytes memory) {
                bytes32 safeTxHash =
                    keccak256(
                        abi.encode(
                            SAFE_TX_TYPEHASH,
                            to,
                            value,
                            keccak256(data),
                            operation,
                            safeTxGas,
                            baseGas,
                            gasPrice,
                            gasToken,
                            refundReceiver,
                            _nonce
                        )
                    );
                return abi.encodePacked(bytes1(0x19), bytes1(0x01), domainSeparator(), safeTxHash);
            }
            /// @dev Returns hash to be signed by owners.
            /// @param to Destination address.
            /// @param value Ether value.
            /// @param data Data payload.
            /// @param operation Operation type.
            /// @param safeTxGas Fas that should be used for the safe transaction.
            /// @param baseGas Gas costs for data used to trigger the safe transaction.
            /// @param gasPrice Maximum gas price that should be used for this transaction.
            /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
            /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
            /// @param _nonce Transaction nonce.
            /// @return Transaction hash.
            function getTransactionHash(
                address to,
                uint256 value,
                bytes calldata data,
                Enum.Operation operation,
                uint256 safeTxGas,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address refundReceiver,
                uint256 _nonce
            ) public view returns (bytes32) {
                return keccak256(encodeTransactionData(to, value, data, operation, safeTxGas, baseGas, gasPrice, gasToken, refundReceiver, _nonce));
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/Enum.sol";
        /// @title Executor - A contract that can execute transactions
        /// @author Richard Meissner - <[email protected]>
        contract Executor {
            function execute(
                address to,
                uint256 value,
                bytes memory data,
                Enum.Operation operation,
                uint256 txGas
            ) internal returns (bool success) {
                if (operation == Enum.Operation.DelegateCall) {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        success := delegatecall(txGas, to, add(data, 0x20), mload(data), 0, 0)
                    }
                } else {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        success := call(txGas, to, value, add(data, 0x20), mload(data), 0, 0)
                    }
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/SelfAuthorized.sol";
        /// @title Fallback Manager - A contract that manages fallback calls made to this contract
        /// @author Richard Meissner - <[email protected]>
        contract FallbackManager is SelfAuthorized {
            event ChangedFallbackHandler(address handler);
            // keccak256("fallback_manager.handler.address")
            bytes32 internal constant FALLBACK_HANDLER_STORAGE_SLOT = 0x6c9a6c4a39284e37ed1cf53d337577d14212a4870fb976a4366c693b939918d5;
            function internalSetFallbackHandler(address handler) internal {
                bytes32 slot = FALLBACK_HANDLER_STORAGE_SLOT;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    sstore(slot, handler)
                }
            }
            /// @dev Allows to add a contract to handle fallback calls.
            ///      Only fallback calls without value and with data will be forwarded.
            ///      This can only be done via a Safe transaction.
            /// @param handler contract to handle fallbacks calls.
            function setFallbackHandler(address handler) public authorized {
                internalSetFallbackHandler(handler);
                emit ChangedFallbackHandler(handler);
            }
            // solhint-disable-next-line payable-fallback,no-complex-fallback
            fallback() external {
                bytes32 slot = FALLBACK_HANDLER_STORAGE_SLOT;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let handler := sload(slot)
                    if iszero(handler) {
                        return(0, 0)
                    }
                    calldatacopy(0, 0, calldatasize())
                    // The msg.sender address is shifted to the left by 12 bytes to remove the padding
                    // Then the address without padding is stored right after the calldata
                    mstore(calldatasize(), shl(96, caller()))
                    // Add 20 bytes for the address appended add the end
                    let success := call(gas(), handler, 0, 0, add(calldatasize(), 20), 0, 0)
                    returndatacopy(0, 0, returndatasize())
                    if iszero(success) {
                        revert(0, returndatasize())
                    }
                    return(0, returndatasize())
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/Enum.sol";
        import "../common/SelfAuthorized.sol";
        interface Guard {
            function checkTransaction(
                address to,
                uint256 value,
                bytes memory data,
                Enum.Operation operation,
                uint256 safeTxGas,
                uint256 baseGas,
                uint256 gasPrice,
                address gasToken,
                address payable refundReceiver,
                bytes memory signatures,
                address msgSender
            ) external;
            function checkAfterExecution(bytes32 txHash, bool success) external;
        }
        /// @title Fallback Manager - A contract that manages fallback calls made to this contract
        /// @author Richard Meissner - <[email protected]>
        contract GuardManager is SelfAuthorized {
            event ChangedGuard(address guard);
            // keccak256("guard_manager.guard.address")
            bytes32 internal constant GUARD_STORAGE_SLOT = 0x4a204f620c8c5ccdca3fd54d003badd85ba500436a431f0cbda4f558c93c34c8;
            /// @dev Set a guard that checks transactions before execution
            /// @param guard The address of the guard to be used or the 0 address to disable the guard
            function setGuard(address guard) external authorized {
                bytes32 slot = GUARD_STORAGE_SLOT;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    sstore(slot, guard)
                }
                emit ChangedGuard(guard);
            }
            function getGuard() internal view returns (address guard) {
                bytes32 slot = GUARD_STORAGE_SLOT;
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    guard := sload(slot)
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/Enum.sol";
        import "../common/SelfAuthorized.sol";
        import "./Executor.sol";
        /// @title Module Manager - A contract that manages modules that can execute transactions via this contract
        /// @author Stefan George - <[email protected]>
        /// @author Richard Meissner - <[email protected]>
        contract ModuleManager is SelfAuthorized, Executor {
            event EnabledModule(address module);
            event DisabledModule(address module);
            event ExecutionFromModuleSuccess(address indexed module);
            event ExecutionFromModuleFailure(address indexed module);
            address internal constant SENTINEL_MODULES = address(0x1);
            mapping(address => address) internal modules;
            function setupModules(address to, bytes memory data) internal {
                require(modules[SENTINEL_MODULES] == address(0), "GS100");
                modules[SENTINEL_MODULES] = SENTINEL_MODULES;
                if (to != address(0))
                    // Setup has to complete successfully or transaction fails.
                    require(execute(to, 0, data, Enum.Operation.DelegateCall, gasleft()), "GS000");
            }
            /// @dev Allows to add a module to the whitelist.
            ///      This can only be done via a Safe transaction.
            /// @notice Enables the module `module` for the Safe.
            /// @param module Module to be whitelisted.
            function enableModule(address module) public authorized {
                // Module address cannot be null or sentinel.
                require(module != address(0) && module != SENTINEL_MODULES, "GS101");
                // Module cannot be added twice.
                require(modules[module] == address(0), "GS102");
                modules[module] = modules[SENTINEL_MODULES];
                modules[SENTINEL_MODULES] = module;
                emit EnabledModule(module);
            }
            /// @dev Allows to remove a module from the whitelist.
            ///      This can only be done via a Safe transaction.
            /// @notice Disables the module `module` for the Safe.
            /// @param prevModule Module that pointed to the module to be removed in the linked list
            /// @param module Module to be removed.
            function disableModule(address prevModule, address module) public authorized {
                // Validate module address and check that it corresponds to module index.
                require(module != address(0) && module != SENTINEL_MODULES, "GS101");
                require(modules[prevModule] == module, "GS103");
                modules[prevModule] = modules[module];
                modules[module] = address(0);
                emit DisabledModule(module);
            }
            /// @dev Allows a Module to execute a Safe transaction without any further confirmations.
            /// @param to Destination address of module transaction.
            /// @param value Ether value of module transaction.
            /// @param data Data payload of module transaction.
            /// @param operation Operation type of module transaction.
            function execTransactionFromModule(
                address to,
                uint256 value,
                bytes memory data,
                Enum.Operation operation
            ) public virtual returns (bool success) {
                // Only whitelisted modules are allowed.
                require(msg.sender != SENTINEL_MODULES && modules[msg.sender] != address(0), "GS104");
                // Execute transaction without further confirmations.
                success = execute(to, value, data, operation, gasleft());
                if (success) emit ExecutionFromModuleSuccess(msg.sender);
                else emit ExecutionFromModuleFailure(msg.sender);
            }
            /// @dev Allows a Module to execute a Safe transaction without any further confirmations and return data
            /// @param to Destination address of module transaction.
            /// @param value Ether value of module transaction.
            /// @param data Data payload of module transaction.
            /// @param operation Operation type of module transaction.
            function execTransactionFromModuleReturnData(
                address to,
                uint256 value,
                bytes memory data,
                Enum.Operation operation
            ) public returns (bool success, bytes memory returnData) {
                success = execTransactionFromModule(to, value, data, operation);
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    // Load free memory location
                    let ptr := mload(0x40)
                    // We allocate memory for the return data by setting the free memory location to
                    // current free memory location + data size + 32 bytes for data size value
                    mstore(0x40, add(ptr, add(returndatasize(), 0x20)))
                    // Store the size
                    mstore(ptr, returndatasize())
                    // Store the data
                    returndatacopy(add(ptr, 0x20), 0, returndatasize())
                    // Point the return data to the correct memory location
                    returnData := ptr
                }
            }
            /// @dev Returns if an module is enabled
            /// @return True if the module is enabled
            function isModuleEnabled(address module) public view returns (bool) {
                return SENTINEL_MODULES != module && modules[module] != address(0);
            }
            /// @dev Returns array of modules.
            /// @param start Start of the page.
            /// @param pageSize Maximum number of modules that should be returned.
            /// @return array Array of modules.
            /// @return next Start of the next page.
            function getModulesPaginated(address start, uint256 pageSize) external view returns (address[] memory array, address next) {
                // Init array with max page size
                array = new address[](pageSize);
                // Populate return array
                uint256 moduleCount = 0;
                address currentModule = modules[start];
                while (currentModule != address(0x0) && currentModule != SENTINEL_MODULES && moduleCount < pageSize) {
                    array[moduleCount] = currentModule;
                    currentModule = modules[currentModule];
                    moduleCount++;
                }
                next = currentModule;
                // Set correct size of returned array
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    mstore(array, moduleCount)
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        import "../common/SelfAuthorized.sol";
        /// @title OwnerManager - Manages a set of owners and a threshold to perform actions.
        /// @author Stefan George - <[email protected]>
        /// @author Richard Meissner - <[email protected]>
        contract OwnerManager is SelfAuthorized {
            event AddedOwner(address owner);
            event RemovedOwner(address owner);
            event ChangedThreshold(uint256 threshold);
            address internal constant SENTINEL_OWNERS = address(0x1);
            mapping(address => address) internal owners;
            uint256 internal ownerCount;
            uint256 internal threshold;
            /// @dev Setup function sets initial storage of contract.
            /// @param _owners List of Safe owners.
            /// @param _threshold Number of required confirmations for a Safe transaction.
            function setupOwners(address[] memory _owners, uint256 _threshold) internal {
                // Threshold can only be 0 at initialization.
                // Check ensures that setup function can only be called once.
                require(threshold == 0, "GS200");
                // Validate that threshold is smaller than number of added owners.
                require(_threshold <= _owners.length, "GS201");
                // There has to be at least one Safe owner.
                require(_threshold >= 1, "GS202");
                // Initializing Safe owners.
                address currentOwner = SENTINEL_OWNERS;
                for (uint256 i = 0; i < _owners.length; i++) {
                    // Owner address cannot be null.
                    address owner = _owners[i];
                    require(owner != address(0) && owner != SENTINEL_OWNERS && owner != address(this) && currentOwner != owner, "GS203");
                    // No duplicate owners allowed.
                    require(owners[owner] == address(0), "GS204");
                    owners[currentOwner] = owner;
                    currentOwner = owner;
                }
                owners[currentOwner] = SENTINEL_OWNERS;
                ownerCount = _owners.length;
                threshold = _threshold;
            }
            /// @dev Allows to add a new owner to the Safe and update the threshold at the same time.
            ///      This can only be done via a Safe transaction.
            /// @notice Adds the owner `owner` to the Safe and updates the threshold to `_threshold`.
            /// @param owner New owner address.
            /// @param _threshold New threshold.
            function addOwnerWithThreshold(address owner, uint256 _threshold) public authorized {
                // Owner address cannot be null, the sentinel or the Safe itself.
                require(owner != address(0) && owner != SENTINEL_OWNERS && owner != address(this), "GS203");
                // No duplicate owners allowed.
                require(owners[owner] == address(0), "GS204");
                owners[owner] = owners[SENTINEL_OWNERS];
                owners[SENTINEL_OWNERS] = owner;
                ownerCount++;
                emit AddedOwner(owner);
                // Change threshold if threshold was changed.
                if (threshold != _threshold) changeThreshold(_threshold);
            }
            /// @dev Allows to remove an owner from the Safe and update the threshold at the same time.
            ///      This can only be done via a Safe transaction.
            /// @notice Removes the owner `owner` from the Safe and updates the threshold to `_threshold`.
            /// @param prevOwner Owner that pointed to the owner to be removed in the linked list
            /// @param owner Owner address to be removed.
            /// @param _threshold New threshold.
            function removeOwner(
                address prevOwner,
                address owner,
                uint256 _threshold
            ) public authorized {
                // Only allow to remove an owner, if threshold can still be reached.
                require(ownerCount - 1 >= _threshold, "GS201");
                // Validate owner address and check that it corresponds to owner index.
                require(owner != address(0) && owner != SENTINEL_OWNERS, "GS203");
                require(owners[prevOwner] == owner, "GS205");
                owners[prevOwner] = owners[owner];
                owners[owner] = address(0);
                ownerCount--;
                emit RemovedOwner(owner);
                // Change threshold if threshold was changed.
                if (threshold != _threshold) changeThreshold(_threshold);
            }
            /// @dev Allows to swap/replace an owner from the Safe with another address.
            ///      This can only be done via a Safe transaction.
            /// @notice Replaces the owner `oldOwner` in the Safe with `newOwner`.
            /// @param prevOwner Owner that pointed to the owner to be replaced in the linked list
            /// @param oldOwner Owner address to be replaced.
            /// @param newOwner New owner address.
            function swapOwner(
                address prevOwner,
                address oldOwner,
                address newOwner
            ) public authorized {
                // Owner address cannot be null, the sentinel or the Safe itself.
                require(newOwner != address(0) && newOwner != SENTINEL_OWNERS && newOwner != address(this), "GS203");
                // No duplicate owners allowed.
                require(owners[newOwner] == address(0), "GS204");
                // Validate oldOwner address and check that it corresponds to owner index.
                require(oldOwner != address(0) && oldOwner != SENTINEL_OWNERS, "GS203");
                require(owners[prevOwner] == oldOwner, "GS205");
                owners[newOwner] = owners[oldOwner];
                owners[prevOwner] = newOwner;
                owners[oldOwner] = address(0);
                emit RemovedOwner(oldOwner);
                emit AddedOwner(newOwner);
            }
            /// @dev Allows to update the number of required confirmations by Safe owners.
            ///      This can only be done via a Safe transaction.
            /// @notice Changes the threshold of the Safe to `_threshold`.
            /// @param _threshold New threshold.
            function changeThreshold(uint256 _threshold) public authorized {
                // Validate that threshold is smaller than number of owners.
                require(_threshold <= ownerCount, "GS201");
                // There has to be at least one Safe owner.
                require(_threshold >= 1, "GS202");
                threshold = _threshold;
                emit ChangedThreshold(threshold);
            }
            function getThreshold() public view returns (uint256) {
                return threshold;
            }
            function isOwner(address owner) public view returns (bool) {
                return owner != SENTINEL_OWNERS && owners[owner] != address(0);
            }
            /// @dev Returns array of owners.
            /// @return Array of Safe owners.
            function getOwners() public view returns (address[] memory) {
                address[] memory array = new address[](ownerCount);
                // populate return array
                uint256 index = 0;
                address currentOwner = owners[SENTINEL_OWNERS];
                while (currentOwner != SENTINEL_OWNERS) {
                    array[index] = currentOwner;
                    currentOwner = owners[currentOwner];
                    index++;
                }
                return array;
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title Enum - Collection of enums
        /// @author Richard Meissner - <[email protected]>
        contract Enum {
            enum Operation {Call, DelegateCall}
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title EtherPaymentFallback - A contract that has a fallback to accept ether payments
        /// @author Richard Meissner - <[email protected]>
        contract EtherPaymentFallback {
            event SafeReceived(address indexed sender, uint256 value);
            /// @dev Fallback function accepts Ether transactions.
            receive() external payable {
                emit SafeReceived(msg.sender, msg.value);
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title SecuredTokenTransfer - Secure token transfer
        /// @author Richard Meissner - <[email protected]>
        contract SecuredTokenTransfer {
            /// @dev Transfers a token and returns if it was a success
            /// @param token Token that should be transferred
            /// @param receiver Receiver to whom the token should be transferred
            /// @param amount The amount of tokens that should be transferred
            function transferToken(
                address token,
                address receiver,
                uint256 amount
            ) internal returns (bool transferred) {
                // 0xa9059cbb - keccack("transfer(address,uint256)")
                bytes memory data = abi.encodeWithSelector(0xa9059cbb, receiver, amount);
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    // We write the return value to scratch space.
                    // See https://docs.soliditylang.org/en/v0.7.6/internals/layout_in_memory.html#layout-in-memory
                    let success := call(sub(gas(), 10000), token, 0, add(data, 0x20), mload(data), 0, 0x20)
                    switch returndatasize()
                        case 0 {
                            transferred := success
                        }
                        case 0x20 {
                            transferred := iszero(or(iszero(success), iszero(mload(0))))
                        }
                        default {
                            transferred := 0
                        }
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title SelfAuthorized - authorizes current contract to perform actions
        /// @author Richard Meissner - <[email protected]>
        contract SelfAuthorized {
            function requireSelfCall() private view {
                require(msg.sender == address(this), "GS031");
            }
            modifier authorized() {
                // This is a function call as it minimized the bytecode size
                requireSelfCall();
                _;
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title SignatureDecoder - Decodes signatures that a encoded as bytes
        /// @author Richard Meissner - <[email protected]>
        contract SignatureDecoder {
            /// @dev divides bytes signature into `uint8 v, bytes32 r, bytes32 s`.
            /// @notice Make sure to peform a bounds check for @param pos, to avoid out of bounds access on @param signatures
            /// @param pos which signature to read. A prior bounds check of this parameter should be performed, to avoid out of bounds access
            /// @param signatures concatenated rsv signatures
            function signatureSplit(bytes memory signatures, uint256 pos)
                internal
                pure
                returns (
                    uint8 v,
                    bytes32 r,
                    bytes32 s
                )
            {
                // The signature format is a compact form of:
                //   {bytes32 r}{bytes32 s}{uint8 v}
                // Compact means, uint8 is not padded to 32 bytes.
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let signaturePos := mul(0x41, pos)
                    r := mload(add(signatures, add(signaturePos, 0x20)))
                    s := mload(add(signatures, add(signaturePos, 0x40)))
                    // Here we are loading the last 32 bytes, including 31 bytes
                    // of 's'. There is no 'mload8' to do this.
                    //
                    // 'byte' is not working due to the Solidity parser, so lets
                    // use the second best option, 'and'
                    v := and(mload(add(signatures, add(signaturePos, 0x41))), 0xff)
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title Singleton - Base for singleton contracts (should always be first super contract)
        ///         This contract is tightly coupled to our proxy contract (see `proxies/GnosisSafeProxy.sol`)
        /// @author Richard Meissner - <[email protected]>
        contract Singleton {
            // singleton always needs to be first declared variable, to ensure that it is at the same location as in the Proxy contract.
            // It should also always be ensured that the address is stored alone (uses a full word)
            address private singleton;
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /// @title StorageAccessible - generic base contract that allows callers to access all internal storage.
        /// @notice See https://github.com/gnosis/util-contracts/blob/bb5fe5fb5df6d8400998094fb1b32a178a47c3a1/contracts/StorageAccessible.sol
        contract StorageAccessible {
            /**
             * @dev Reads `length` bytes of storage in the currents contract
             * @param offset - the offset in the current contract's storage in words to start reading from
             * @param length - the number of words (32 bytes) of data to read
             * @return the bytes that were read.
             */
            function getStorageAt(uint256 offset, uint256 length) public view returns (bytes memory) {
                bytes memory result = new bytes(length * 32);
                for (uint256 index = 0; index < length; index++) {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        let word := sload(add(offset, index))
                        mstore(add(add(result, 0x20), mul(index, 0x20)), word)
                    }
                }
                return result;
            }
            /**
             * @dev Performs a delegetecall on a targetContract in the context of self.
             * Internally reverts execution to avoid side effects (making it static).
             *
             * This method reverts with data equal to `abi.encode(bool(success), bytes(response))`.
             * Specifically, the `returndata` after a call to this method will be:
             * `success:bool || response.length:uint256 || response:bytes`.
             *
             * @param targetContract Address of the contract containing the code to execute.
             * @param calldataPayload Calldata that should be sent to the target contract (encoded method name and arguments).
             */
            function simulateAndRevert(address targetContract, bytes memory calldataPayload) external {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let success := delegatecall(gas(), targetContract, add(calldataPayload, 0x20), mload(calldataPayload), 0, 0)
                    mstore(0x00, success)
                    mstore(0x20, returndatasize())
                    returndatacopy(0x40, 0, returndatasize())
                    revert(0, add(returndatasize(), 0x40))
                }
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        /**
         * @title GnosisSafeMath
         * @dev Math operations with safety checks that revert on error
         * Renamed from SafeMath to GnosisSafeMath to avoid conflicts
         * TODO: remove once open zeppelin update to solc 0.5.0
         */
        library GnosisSafeMath {
            /**
             * @dev Multiplies two numbers, reverts on overflow.
             */
            function mul(uint256 a, uint256 b) internal pure returns (uint256) {
                // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
                // benefit is lost if 'b' is also tested.
                // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
                if (a == 0) {
                    return 0;
                }
                uint256 c = a * b;
                require(c / a == b);
                return c;
            }
            /**
             * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
             */
            function sub(uint256 a, uint256 b) internal pure returns (uint256) {
                require(b <= a);
                uint256 c = a - b;
                return c;
            }
            /**
             * @dev Adds two numbers, reverts on overflow.
             */
            function add(uint256 a, uint256 b) internal pure returns (uint256) {
                uint256 c = a + b;
                require(c >= a);
                return c;
            }
            /**
             * @dev Returns the largest of two numbers.
             */
            function max(uint256 a, uint256 b) internal pure returns (uint256) {
                return a >= b ? a : b;
            }
        }
        // SPDX-License-Identifier: LGPL-3.0-only
        pragma solidity >=0.7.0 <0.9.0;
        contract ISignatureValidatorConstants {
            // bytes4(keccak256("isValidSignature(bytes,bytes)")
            bytes4 internal constant EIP1271_MAGIC_VALUE = 0x20c13b0b;
        }
        abstract contract ISignatureValidator is ISignatureValidatorConstants {
            /**
             * @dev Should return whether the signature provided is valid for the provided data
             * @param _data Arbitrary length data signed on the behalf of address(this)
             * @param _signature Signature byte array associated with _data
             *
             * MUST return the bytes4 magic value 0x20c13b0b when function passes.
             * MUST NOT modify state (using STATICCALL for solc < 0.5, view modifier for solc > 0.5)
             * MUST allow external calls
             */
            function isValidSignature(bytes memory _data, bytes memory _signature) public view virtual returns (bytes4);
        }