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Contract Name:
YBOYZ

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/**

Twitter: https://twitter.com/YardBoyzERCYB
Telegram: https://t.me/YardBoyzPortal
Website: https://yardboyz.xyz

*/

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

interface IUniswapV2Router02 {
    function factory() external pure returns (address);

    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
    external
    returns (
        uint256 amountA,
        uint256 amountB,
        uint256 liquidity
    );

    function addLiquidityETH(
        address token,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
    external
    payable
    returns (
        uint256 amountToken,
        uint256 amountETH,
        uint256 liquidity
    );

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
}


/// @notice Library for storage of packed unsigned integers.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/LibMap.sol)
library LibMap {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                          STRUCTS                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev A uint8 map in storage.
    struct Uint8Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint16 map in storage.
    struct Uint16Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint32 map in storage.
    struct Uint32Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint40 map in storage. Useful for storing timestamps up to 34841 A.D.
    struct Uint40Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint64 map in storage.
    struct Uint64Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint128 map in storage.
    struct Uint128Map {
        mapping(uint256 => uint256) map;
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     GETTERS / SETTERS                      */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the uint8 value at `index` in `map`.
    function get(Uint8Map storage map, uint256 index) internal view returns (uint8 result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(5, index))
            result := byte(and(31, not(index)), sload(keccak256(0x00, 0x40)))
        }
    }

    /// @dev Updates the uint8 value at `index` in `map`.
    function set(Uint8Map storage map, uint256 index, uint8 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(5, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            mstore(0x00, sload(s))
            mstore8(and(31, not(index)), value)
            sstore(s, mload(0x00))
        }
    }

    /// @dev Returns the uint16 value at `index` in `map`.
    function get(Uint16Map storage map, uint256 index) internal view returns (uint16 result) {
        result = uint16(map.map[index >> 4] >> ((index & 15) << 4));
    }

    /// @dev Updates the uint16 value at `index` in `map`.
    function set(Uint16Map storage map, uint256 index, uint16 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(4, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(4, and(index, 15)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the uint32 value at `index` in `map`.
    function get(Uint32Map storage map, uint256 index) internal view returns (uint32 result) {
        result = uint32(map.map[index >> 3] >> ((index & 7) << 5));
    }

    /// @dev Updates the uint32 value at `index` in `map`.
    function set(Uint32Map storage map, uint256 index, uint32 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(3, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(5, and(index, 7)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the uint40 value at `index` in `map`.
    function get(Uint40Map storage map, uint256 index) internal view returns (uint40 result) {
        unchecked {
            result = uint40(map.map[index / 6] >> ((index % 6) * 40));
        }
    }

    /// @dev Updates the uint40 value at `index` in `map`.
    function set(Uint40Map storage map, uint256 index, uint40 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, div(index, 6))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := mul(40, mod(index, 6)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the uint64 value at `index` in `map`.
    function get(Uint64Map storage map, uint256 index) internal view returns (uint64 result) {
        result = uint64(map.map[index >> 2] >> ((index & 3) << 6));
    }

    /// @dev Updates the uint64 value at `index` in `map`.
    function set(Uint64Map storage map, uint256 index, uint64 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(2, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(6, and(index, 3)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the uint128 value at `index` in `map`.
    function get(Uint128Map storage map, uint256 index) internal view returns (uint128 result) {
        result = uint128(map.map[index >> 1] >> ((index & 1) << 7));
    }

    /// @dev Updates the uint128 value at `index` in `map`.
    function set(Uint128Map storage map, uint256 index, uint128 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(1, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(7, and(index, 1)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffffffffffffffffffffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the value at `index` in `map`.
    function get(mapping(uint256 => uint256) storage map, uint256 index, uint256 bitWidth)
    internal
    view
    returns (uint256 result)
    {
        unchecked {
            uint256 d = _rawDiv(256, bitWidth); // Bucket size.
            uint256 m = (1 << bitWidth) - 1; // Value mask.
            result = (map[_rawDiv(index, d)] >> (_rawMod(index, d) * bitWidth)) & m;
        }
    }

    /// @dev Updates the value at `index` in `map`.
    function set(
        mapping(uint256 => uint256) storage map,
        uint256 index,
        uint256 value,
        uint256 bitWidth
    ) internal {
        unchecked {
            uint256 d = _rawDiv(256, bitWidth); // Bucket size.
            uint256 m = (1 << bitWidth) - 1; // Value mask.
            uint256 o = _rawMod(index, d) * bitWidth; // Storage slot offset (bits).
            map[_rawDiv(index, d)] ^= (((map[_rawDiv(index, d)] >> o) ^ value) & m) << o;
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                       BINARY SEARCH                        */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // The following functions search in the range of [`start`, `end`)
    // (i.e. `start <= index < end`).
    // The range must be sorted in ascending order.
    // `index` precedence: equal to > nearest before > nearest after.
    // An invalid search range will simply return `(found = false, index = start)`.

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint8Map storage map, uint8 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 8);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint16Map storage map, uint16 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 16);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint32Map storage map, uint32 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 32);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint40Map storage map, uint40 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 40);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint64Map storage map, uint64 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 64);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint128Map storage map, uint128 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 128);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(
        mapping(uint256 => uint256) storage map,
        uint256 needle,
        uint256 start,
        uint256 end,
        uint256 bitWidth
    ) internal view returns (bool found, uint256 index) {
        unchecked {
            if (start >= end) end = start;
            uint256 t;
            uint256 o = start - 1; // Offset to derive the actual index.
            uint256 l = 1; // Low.
            uint256 d = _rawDiv(256, bitWidth); // Bucket size.
            uint256 m = (1 << bitWidth) - 1; // Value mask.
            uint256 h = end - start; // High.
            while (true) {
                index = (l & h) + ((l ^ h) >> 1);
                if (l > h) break;
                t = (map[_rawDiv(index + o, d)] >> (_rawMod(index + o, d) * bitWidth)) & m;
                if (t == needle) break;
                if (needle <= t) h = index - 1;
                else l = index + 1;
            }
        /// @solidity memory-safe-assembly
            assembly {
                m := or(iszero(index), iszero(bitWidth))
                found := iszero(or(xor(t, needle), m))
                index := add(o, xor(index, mul(xor(index, 1), m)))
            }
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                      PRIVATE HELPERS                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns `x / y`, returning 0 if `y` is zero.
    function _rawDiv(uint256 x, uint256 y) private pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            z := div(x, y)
        }
    }

    /// @dev Returns `x % y`, returning 0 if `y` is zero.
    function _rawMod(uint256 x, uint256 y) private pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            z := mod(x, y)
        }
    }
}

/// @notice Library for converting numbers into strings and other string operations.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/LibString.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/LibString.sol)
///
/// @dev Note:
/// For performance and bytecode compactness, most of the string operations are restricted to
/// byte strings (7-bit ASCII), except where otherwise specified.
/// Usage of byte string operations on charsets with runes spanning two or more bytes
/// can lead to undefined behavior.
library LibString {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                        CUSTOM ERRORS                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The length of the output is too small to contain all the hex digits.
    error HexLengthInsufficient();

    /// @dev The length of the string is more than 32 bytes.
    error TooBigForSmallString();

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         CONSTANTS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The constant returned when the `search` is not found in the string.
    uint256 internal constant NOT_FOUND = type(uint256).max;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     DECIMAL OPERATIONS                     */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the base 10 decimal representation of `value`.
    function toString(uint256 value) internal pure returns (string memory str) {
        /// @solidity memory-safe-assembly
        assembly {
        // The maximum value of a uint256 contains 78 digits (1 byte per digit), but
        // we allocate 0xa0 bytes to keep the free memory pointer 32-byte word aligned.
        // We will need 1 word for the trailing zeros padding, 1 word for the length,
        // and 3 words for a maximum of 78 digits.
            str := add(mload(0x40), 0x80)
        // Update the free memory pointer to allocate.
            mstore(0x40, add(str, 0x20))
        // Zeroize the slot after the string.
            mstore(str, 0)

        // Cache the end of the memory to calculate the length later.
            let end := str

            let w := not(0) // Tsk.
        // We write the string from rightmost digit to leftmost digit.
        // The following is essentially a do-while loop that also handles the zero case.
            for { let temp := value } 1 {} {
                str := add(str, w) // `sub(str, 1)`.
            // Write the character to the pointer.
            // The ASCII index of the '0' character is 48.
                mstore8(str, add(48, mod(temp, 10)))
            // Keep dividing `temp` until zero.
                temp := div(temp, 10)
                if iszero(temp) { break }
            }

            let length := sub(end, str)
        // Move the pointer 32 bytes leftwards to make room for the length.
            str := sub(str, 0x20)
        // Store the length.
            mstore(str, length)
        }
    }

    /// @dev Returns the base 10 decimal representation of `value`.
    function toString(int256 value) internal pure returns (string memory str) {
        if (value >= 0) {
            return toString(uint256(value));
        }
        unchecked {
            str = toString(~uint256(value) + 1);
        }
        /// @solidity memory-safe-assembly
        assembly {
        // We still have some spare memory space on the left,
        // as we have allocated 3 words (96 bytes) for up to 78 digits.
            let length := mload(str) // Load the string length.
            mstore(str, 0x2d) // Store the '-' character.
            str := sub(str, 1) // Move back the string pointer by a byte.
            mstore(str, add(length, 1)) // Update the string length.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   HEXADECIMAL OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the hexadecimal representation of `value`,
    /// left-padded to an input length of `length` bytes.
    /// The output is prefixed with "0x" encoded using 2 hexadecimal digits per byte,
    /// giving a total length of `length * 2 + 2` bytes.
    /// Reverts if `length` is too small for the output to contain all the digits.
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value, length);
        /// @solidity memory-safe-assembly
        assembly {
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(str, 0x3078) // Write the "0x" prefix.
            str := sub(str, 2) // Move the pointer.
            mstore(str, strLength) // Write the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`,
    /// left-padded to an input length of `length` bytes.
    /// The output is prefixed with "0x" encoded using 2 hexadecimal digits per byte,
    /// giving a total length of `length * 2` bytes.
    /// Reverts if `length` is too small for the output to contain all the digits.
    function toHexStringNoPrefix(uint256 value, uint256 length)
    internal
    pure
    returns (string memory str)
    {
        /// @solidity memory-safe-assembly
        assembly {
        // We need 0x20 bytes for the trailing zeros padding, `length * 2` bytes
        // for the digits, 0x02 bytes for the prefix, and 0x20 bytes for the length.
        // We add 0x20 to the total and round down to a multiple of 0x20.
        // (0x20 + 0x20 + 0x02 + 0x20) = 0x62.
            str := add(mload(0x40), and(add(shl(1, length), 0x42), not(0x1f)))
        // Allocate the memory.
            mstore(0x40, add(str, 0x20))
        // Zeroize the slot after the string.
            mstore(str, 0)

        // Cache the end to calculate the length later.
            let end := str
        // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            let start := sub(str, add(length, length))
            let w := not(1) // Tsk.
            let temp := value
        // We write the string from rightmost digit to leftmost digit.
        // The following is essentially a do-while loop that also handles the zero case.
            for {} 1 {} {
                str := add(str, w) // `sub(str, 2)`.
                mstore8(add(str, 1), mload(and(temp, 15)))
                mstore8(str, mload(and(shr(4, temp), 15)))
                temp := shr(8, temp)
                if iszero(xor(str, start)) { break }
            }

            if temp {
                mstore(0x00, 0x2194895a) // `HexLengthInsufficient()`.
                revert(0x1c, 0x04)
            }

        // Compute the string's length.
            let strLength := sub(end, str)
        // Move the pointer and write the length.
            str := sub(str, 0x20)
            mstore(str, strLength)
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x" and encoded using 2 hexadecimal digits per byte.
    /// As address are 20 bytes long, the output will left-padded to have
    /// a length of `20 * 2 + 2` bytes.
    function toHexString(uint256 value) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(str, 0x3078) // Write the "0x" prefix.
            str := sub(str, 2) // Move the pointer.
            mstore(str, strLength) // Write the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x".
    /// The output excludes leading "0" from the `toHexString` output.
    /// `0x00: "0x0", 0x01: "0x1", 0x12: "0x12", 0x123: "0x123"`.
    function toMinimalHexString(uint256 value) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let o := eq(byte(0, mload(add(str, 0x20))), 0x30) // Whether leading zero is present.
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(add(str, o), 0x3078) // Write the "0x" prefix, accounting for leading zero.
            str := sub(add(str, o), 2) // Move the pointer, accounting for leading zero.
            mstore(str, sub(strLength, o)) // Write the length, accounting for leading zero.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output excludes leading "0" from the `toHexStringNoPrefix` output.
    /// `0x00: "0", 0x01: "1", 0x12: "12", 0x123: "123"`.
    function toMinimalHexStringNoPrefix(uint256 value) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let o := eq(byte(0, mload(add(str, 0x20))), 0x30) // Whether leading zero is present.
            let strLength := mload(str) // Get the length.
            str := add(str, o) // Move the pointer, accounting for leading zero.
            mstore(str, sub(strLength, o)) // Write the length, accounting for leading zero.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is encoded using 2 hexadecimal digits per byte.
    /// As address are 20 bytes long, the output will left-padded to have
    /// a length of `20 * 2` bytes.
    function toHexStringNoPrefix(uint256 value) internal pure returns (string memory str) {
        /// @solidity memory-safe-assembly
        assembly {
        // We need 0x20 bytes for the trailing zeros padding, 0x20 bytes for the length,
        // 0x02 bytes for the prefix, and 0x40 bytes for the digits.
        // The next multiple of 0x20 above (0x20 + 0x20 + 0x02 + 0x40) is 0xa0.
            str := add(mload(0x40), 0x80)
        // Allocate the memory.
            mstore(0x40, add(str, 0x20))
        // Zeroize the slot after the string.
            mstore(str, 0)

        // Cache the end to calculate the length later.
            let end := str
        // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            let w := not(1) // Tsk.
        // We write the string from rightmost digit to leftmost digit.
        // The following is essentially a do-while loop that also handles the zero case.
            for { let temp := value } 1 {} {
                str := add(str, w) // `sub(str, 2)`.
                mstore8(add(str, 1), mload(and(temp, 15)))
                mstore8(str, mload(and(shr(4, temp), 15)))
                temp := shr(8, temp)
                if iszero(temp) { break }
            }

        // Compute the string's length.
            let strLength := sub(end, str)
        // Move the pointer and write the length.
            str := sub(str, 0x20)
            mstore(str, strLength)
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x", encoded using 2 hexadecimal digits per byte,
    /// and the alphabets are capitalized conditionally according to
    /// https://eips.ethereum.org/EIPS/eip-55
    function toHexStringChecksummed(address value) internal pure returns (string memory str) {
        str = toHexString(value);
        /// @solidity memory-safe-assembly
        assembly {
            let mask := shl(6, div(not(0), 255)) // `0b010000000100000000 ...`
            let o := add(str, 0x22)
            let hashed := and(keccak256(o, 40), mul(34, mask)) // `0b10001000 ... `
            let t := shl(240, 136) // `0b10001000 << 240`
            for { let i := 0 } 1 {} {
                mstore(add(i, i), mul(t, byte(i, hashed)))
                i := add(i, 1)
                if eq(i, 20) { break }
            }
            mstore(o, xor(mload(o), shr(1, and(mload(0x00), and(mload(o), mask)))))
            o := add(o, 0x20)
            mstore(o, xor(mload(o), shr(1, and(mload(0x20), and(mload(o), mask)))))
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x" and encoded using 2 hexadecimal digits per byte.
    function toHexString(address value) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(str, 0x3078) // Write the "0x" prefix.
            str := sub(str, 2) // Move the pointer.
            mstore(str, strLength) // Write the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexStringNoPrefix(address value) internal pure returns (string memory str) {
        /// @solidity memory-safe-assembly
        assembly {
            str := mload(0x40)

        // Allocate the memory.
        // We need 0x20 bytes for the trailing zeros padding, 0x20 bytes for the length,
        // 0x02 bytes for the prefix, and 0x28 bytes for the digits.
        // The next multiple of 0x20 above (0x20 + 0x20 + 0x02 + 0x28) is 0x80.
            mstore(0x40, add(str, 0x80))

        // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            str := add(str, 2)
            mstore(str, 40)

            let o := add(str, 0x20)
            mstore(add(o, 40), 0)

            value := shl(96, value)

        // We write the string from rightmost digit to leftmost digit.
        // The following is essentially a do-while loop that also handles the zero case.
            for { let i := 0 } 1 {} {
                let p := add(o, add(i, i))
                let temp := byte(i, value)
                mstore8(add(p, 1), mload(and(temp, 15)))
                mstore8(p, mload(shr(4, temp)))
                i := add(i, 1)
                if eq(i, 20) { break }
            }
        }
    }

    /// @dev Returns the hex encoded string from the raw bytes.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexString(bytes memory raw) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(raw);
        /// @solidity memory-safe-assembly
        assembly {
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(str, 0x3078) // Write the "0x" prefix.
            str := sub(str, 2) // Move the pointer.
            mstore(str, strLength) // Write the length.
        }
    }

    /// @dev Returns the hex encoded string from the raw bytes.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexStringNoPrefix(bytes memory raw) internal pure returns (string memory str) {
        /// @solidity memory-safe-assembly
        assembly {
            let length := mload(raw)
            str := add(mload(0x40), 2) // Skip 2 bytes for the optional prefix.
            mstore(str, add(length, length)) // Store the length of the output.

        // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            let o := add(str, 0x20)
            let end := add(raw, length)

            for {} iszero(eq(raw, end)) {} {
                raw := add(raw, 1)
                mstore8(add(o, 1), mload(and(mload(raw), 15)))
                mstore8(o, mload(and(shr(4, mload(raw)), 15)))
                o := add(o, 2)
            }
            mstore(o, 0) // Zeroize the slot after the string.
            mstore(0x40, add(o, 0x20)) // Allocate the memory.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   RUNE STRING OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the number of UTF characters in the string.
    function runeCount(string memory s) internal pure returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            if mload(s) {
                mstore(0x00, div(not(0), 255))
                mstore(0x20, 0x0202020202020202020202020202020202020202020202020303030304040506)
                let o := add(s, 0x20)
                let end := add(o, mload(s))
                for { result := 1 } 1 { result := add(result, 1) } {
                    o := add(o, byte(0, mload(shr(250, mload(o)))))
                    if iszero(lt(o, end)) { break }
                }
            }
        }
    }

    /// @dev Returns if this string is a 7-bit ASCII string.
    /// (i.e. all characters codes are in [0..127])
    function is7BitASCII(string memory s) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            let mask := shl(7, div(not(0), 255))
            result := 1
            let n := mload(s)
            if n {
                let o := add(s, 0x20)
                let end := add(o, n)
                let last := mload(end)
                mstore(end, 0)
                for {} 1 {} {
                    if and(mask, mload(o)) {
                        result := 0
                        break
                    }
                    o := add(o, 0x20)
                    if iszero(lt(o, end)) { break }
                }
                mstore(end, last)
            }
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   BYTE STRING OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // For performance and bytecode compactness, byte string operations are restricted
    // to 7-bit ASCII strings. All offsets are byte offsets, not UTF character offsets.
    // Usage of byte string operations on charsets with runes spanning two or more bytes
    // can lead to undefined behavior.

    /// @dev Returns `subject` all occurrences of `search` replaced with `replacement`.
    function replace(string memory subject, string memory search, string memory replacement)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLength := mload(subject)
            let searchLength := mload(search)
            let replacementLength := mload(replacement)

            subject := add(subject, 0x20)
            search := add(search, 0x20)
            replacement := add(replacement, 0x20)
            result := add(mload(0x40), 0x20)

            let subjectEnd := add(subject, subjectLength)
            if iszero(gt(searchLength, subjectLength)) {
                let subjectSearchEnd := add(sub(subjectEnd, searchLength), 1)
                let h := 0
                if iszero(lt(searchLength, 0x20)) { h := keccak256(search, searchLength) }
                let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
                let s := mload(search)
                for {} 1 {} {
                    let t := mload(subject)
                // Whether the first `searchLength % 32` bytes of
                // `subject` and `search` matches.
                    if iszero(shr(m, xor(t, s))) {
                        if h {
                            if iszero(eq(keccak256(subject, searchLength), h)) {
                                mstore(result, t)
                                result := add(result, 1)
                                subject := add(subject, 1)
                                if iszero(lt(subject, subjectSearchEnd)) { break }
                                continue
                            }
                        }
                    // Copy the `replacement` one word at a time.
                        for { let o := 0 } 1 {} {
                            mstore(add(result, o), mload(add(replacement, o)))
                            o := add(o, 0x20)
                            if iszero(lt(o, replacementLength)) { break }
                        }
                        result := add(result, replacementLength)
                        subject := add(subject, searchLength)
                        if searchLength {
                            if iszero(lt(subject, subjectSearchEnd)) { break }
                            continue
                        }
                    }
                    mstore(result, t)
                    result := add(result, 1)
                    subject := add(subject, 1)
                    if iszero(lt(subject, subjectSearchEnd)) { break }
                }
            }

            let resultRemainder := result
            result := add(mload(0x40), 0x20)
            let k := add(sub(resultRemainder, result), sub(subjectEnd, subject))
        // Copy the rest of the string one word at a time.
            for {} lt(subject, subjectEnd) {} {
                mstore(resultRemainder, mload(subject))
                resultRemainder := add(resultRemainder, 0x20)
                subject := add(subject, 0x20)
            }
            result := sub(result, 0x20)
            let last := add(add(result, 0x20), k) // Zeroize the slot after the string.
            mstore(last, 0)
            mstore(0x40, add(last, 0x20)) // Allocate the memory.
            mstore(result, k) // Store the length.
        }
    }

    /// @dev Returns the byte index of the first location of `search` in `subject`,
    /// searching from left to right, starting from `from`.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
    function indexOf(string memory subject, string memory search, uint256 from)
    internal
    pure
    returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for { let subjectLength := mload(subject) } 1 {} {
                if iszero(mload(search)) {
                    if iszero(gt(from, subjectLength)) {
                        result := from
                        break
                    }
                    result := subjectLength
                    break
                }
                let searchLength := mload(search)
                let subjectStart := add(subject, 0x20)

                result := not(0) // Initialize to `NOT_FOUND`.

                subject := add(subjectStart, from)
                let end := add(sub(add(subjectStart, subjectLength), searchLength), 1)

                let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
                let s := mload(add(search, 0x20))

                if iszero(and(lt(subject, end), lt(from, subjectLength))) { break }

                if iszero(lt(searchLength, 0x20)) {
                    for { let h := keccak256(add(search, 0x20), searchLength) } 1 {} {
                        if iszero(shr(m, xor(mload(subject), s))) {
                            if eq(keccak256(subject, searchLength), h) {
                                result := sub(subject, subjectStart)
                                break
                            }
                        }
                        subject := add(subject, 1)
                        if iszero(lt(subject, end)) { break }
                    }
                    break
                }
                for {} 1 {} {
                    if iszero(shr(m, xor(mload(subject), s))) {
                        result := sub(subject, subjectStart)
                        break
                    }
                    subject := add(subject, 1)
                    if iszero(lt(subject, end)) { break }
                }
                break
            }
        }
    }

    /// @dev Returns the byte index of the first location of `search` in `subject`,
    /// searching from left to right.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
    function indexOf(string memory subject, string memory search)
    internal
    pure
    returns (uint256 result)
    {
        result = indexOf(subject, search, 0);
    }

    /// @dev Returns the byte index of the first location of `search` in `subject`,
    /// searching from right to left, starting from `from`.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
    function lastIndexOf(string memory subject, string memory search, uint256 from)
    internal
    pure
    returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for {} 1 {} {
                result := not(0) // Initialize to `NOT_FOUND`.
                let searchLength := mload(search)
                if gt(searchLength, mload(subject)) { break }
                let w := result

                let fromMax := sub(mload(subject), searchLength)
                if iszero(gt(fromMax, from)) { from := fromMax }

                let end := add(add(subject, 0x20), w)
                subject := add(add(subject, 0x20), from)
                if iszero(gt(subject, end)) { break }
            // As this function is not too often used,
            // we shall simply use keccak256 for smaller bytecode size.
                for { let h := keccak256(add(search, 0x20), searchLength) } 1 {} {
                    if eq(keccak256(subject, searchLength), h) {
                        result := sub(subject, add(end, 1))
                        break
                    }
                    subject := add(subject, w) // `sub(subject, 1)`.
                    if iszero(gt(subject, end)) { break }
                }
                break
            }
        }
    }

    /// @dev Returns the byte index of the first location of `search` in `subject`,
    /// searching from right to left.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
    function lastIndexOf(string memory subject, string memory search)
    internal
    pure
    returns (uint256 result)
    {
        result = lastIndexOf(subject, search, uint256(int256(-1)));
    }

    /// @dev Returns true if `search` is found in `subject`, false otherwise.
    function contains(string memory subject, string memory search) internal pure returns (bool) {
        return indexOf(subject, search) != NOT_FOUND;
    }

    /// @dev Returns whether `subject` starts with `search`.
    function startsWith(string memory subject, string memory search)
    internal
    pure
    returns (bool result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let searchLength := mload(search)
        // Just using keccak256 directly is actually cheaper.
        // forgefmt: disable-next-item
            result := and(
                iszero(gt(searchLength, mload(subject))),
                eq(
                    keccak256(add(subject, 0x20), searchLength),
                    keccak256(add(search, 0x20), searchLength)
                )
            )
        }
    }

    /// @dev Returns whether `subject` ends with `search`.
    function endsWith(string memory subject, string memory search)
    internal
    pure
    returns (bool result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let searchLength := mload(search)
            let subjectLength := mload(subject)
        // Whether `search` is not longer than `subject`.
            let withinRange := iszero(gt(searchLength, subjectLength))
        // Just using keccak256 directly is actually cheaper.
        // forgefmt: disable-next-item
            result := and(
                withinRange,
                eq(
                    keccak256(
                    // `subject + 0x20 + max(subjectLength - searchLength, 0)`.
                        add(add(subject, 0x20), mul(withinRange, sub(subjectLength, searchLength))),
                        searchLength
                    ),
                    keccak256(add(search, 0x20), searchLength)
                )
            )
        }
    }

    /// @dev Returns `subject` repeated `times`.
    function repeat(string memory subject, uint256 times)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLength := mload(subject)
            if iszero(or(iszero(times), iszero(subjectLength))) {
                subject := add(subject, 0x20)
                result := mload(0x40)
                let output := add(result, 0x20)
                for {} 1 {} {
                // Copy the `subject` one word at a time.
                    for { let o := 0 } 1 {} {
                        mstore(add(output, o), mload(add(subject, o)))
                        o := add(o, 0x20)
                        if iszero(lt(o, subjectLength)) { break }
                    }
                    output := add(output, subjectLength)
                    times := sub(times, 1)
                    if iszero(times) { break }
                }
                mstore(output, 0) // Zeroize the slot after the string.
                let resultLength := sub(output, add(result, 0x20))
                mstore(result, resultLength) // Store the length.
            // Allocate the memory.
                mstore(0x40, add(result, add(resultLength, 0x20)))
            }
        }
    }

    /// @dev Returns a copy of `subject` sliced from `start` to `end` (exclusive).
    /// `start` and `end` are byte offsets.
    function slice(string memory subject, uint256 start, uint256 end)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLength := mload(subject)
            if iszero(gt(subjectLength, end)) { end := subjectLength }
            if iszero(gt(subjectLength, start)) { start := subjectLength }
            if lt(start, end) {
                result := mload(0x40)
                let resultLength := sub(end, start)
                mstore(result, resultLength)
                subject := add(subject, start)
                let w := not(0x1f)
            // Copy the `subject` one word at a time, backwards.
                for { let o := and(add(resultLength, 0x1f), w) } 1 {} {
                    mstore(add(result, o), mload(add(subject, o)))
                    o := add(o, w) // `sub(o, 0x20)`.
                    if iszero(o) { break }
                }
            // Zeroize the slot after the string.
                mstore(add(add(result, 0x20), resultLength), 0)
            // Allocate memory for the length and the bytes,
            // rounded up to a multiple of 32.
                mstore(0x40, add(result, and(add(resultLength, 0x3f), w)))
            }
        }
    }

    /// @dev Returns a copy of `subject` sliced from `start` to the end of the string.
    /// `start` is a byte offset.
    function slice(string memory subject, uint256 start)
    internal
    pure
    returns (string memory result)
    {
        result = slice(subject, start, uint256(int256(-1)));
    }

    /// @dev Returns all the indices of `search` in `subject`.
    /// The indices are byte offsets.
    function indicesOf(string memory subject, string memory search)
    internal
    pure
    returns (uint256[] memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLength := mload(subject)
            let searchLength := mload(search)

            if iszero(gt(searchLength, subjectLength)) {
                subject := add(subject, 0x20)
                search := add(search, 0x20)
                result := add(mload(0x40), 0x20)

                let subjectStart := subject
                let subjectSearchEnd := add(sub(add(subject, subjectLength), searchLength), 1)
                let h := 0
                if iszero(lt(searchLength, 0x20)) { h := keccak256(search, searchLength) }
                let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
                let s := mload(search)
                for {} 1 {} {
                    let t := mload(subject)
                // Whether the first `searchLength % 32` bytes of
                // `subject` and `search` matches.
                    if iszero(shr(m, xor(t, s))) {
                        if h {
                            if iszero(eq(keccak256(subject, searchLength), h)) {
                                subject := add(subject, 1)
                                if iszero(lt(subject, subjectSearchEnd)) { break }
                                continue
                            }
                        }
                    // Append to `result`.
                        mstore(result, sub(subject, subjectStart))
                        result := add(result, 0x20)
                    // Advance `subject` by `searchLength`.
                        subject := add(subject, searchLength)
                        if searchLength {
                            if iszero(lt(subject, subjectSearchEnd)) { break }
                            continue
                        }
                    }
                    subject := add(subject, 1)
                    if iszero(lt(subject, subjectSearchEnd)) { break }
                }
                let resultEnd := result
            // Assign `result` to the free memory pointer.
                result := mload(0x40)
            // Store the length of `result`.
                mstore(result, shr(5, sub(resultEnd, add(result, 0x20))))
            // Allocate memory for result.
            // We allocate one more word, so this array can be recycled for {split}.
                mstore(0x40, add(resultEnd, 0x20))
            }
        }
    }

    /// @dev Returns a arrays of strings based on the `delimiter` inside of the `subject` string.
    function split(string memory subject, string memory delimiter)
    internal
    pure
    returns (string[] memory result)
    {
        uint256[] memory indices = indicesOf(subject, delimiter);
        /// @solidity memory-safe-assembly
        assembly {
            let w := not(0x1f)
            let indexPtr := add(indices, 0x20)
            let indicesEnd := add(indexPtr, shl(5, add(mload(indices), 1)))
            mstore(add(indicesEnd, w), mload(subject))
            mstore(indices, add(mload(indices), 1))
            let prevIndex := 0
            for {} 1 {} {
                let index := mload(indexPtr)
                mstore(indexPtr, 0x60)
                if iszero(eq(index, prevIndex)) {
                    let element := mload(0x40)
                    let elementLength := sub(index, prevIndex)
                    mstore(element, elementLength)
                // Copy the `subject` one word at a time, backwards.
                    for { let o := and(add(elementLength, 0x1f), w) } 1 {} {
                        mstore(add(element, o), mload(add(add(subject, prevIndex), o)))
                        o := add(o, w) // `sub(o, 0x20)`.
                        if iszero(o) { break }
                    }
                // Zeroize the slot after the string.
                    mstore(add(add(element, 0x20), elementLength), 0)
                // Allocate memory for the length and the bytes,
                // rounded up to a multiple of 32.
                    mstore(0x40, add(element, and(add(elementLength, 0x3f), w)))
                // Store the `element` into the array.
                    mstore(indexPtr, element)
                }
                prevIndex := add(index, mload(delimiter))
                indexPtr := add(indexPtr, 0x20)
                if iszero(lt(indexPtr, indicesEnd)) { break }
            }
            result := indices
            if iszero(mload(delimiter)) {
                result := add(indices, 0x20)
                mstore(result, sub(mload(indices), 2))
            }
        }
    }

    /// @dev Returns a concatenated string of `a` and `b`.
    /// Cheaper than `string.concat()` and does not de-align the free memory pointer.
    function concat(string memory a, string memory b)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let w := not(0x1f)
            result := mload(0x40)
            let aLength := mload(a)
        // Copy `a` one word at a time, backwards.
            for { let o := and(add(aLength, 0x20), w) } 1 {} {
                mstore(add(result, o), mload(add(a, o)))
                o := add(o, w) // `sub(o, 0x20)`.
                if iszero(o) { break }
            }
            let bLength := mload(b)
            let output := add(result, aLength)
        // Copy `b` one word at a time, backwards.
            for { let o := and(add(bLength, 0x20), w) } 1 {} {
                mstore(add(output, o), mload(add(b, o)))
                o := add(o, w) // `sub(o, 0x20)`.
                if iszero(o) { break }
            }
            let totalLength := add(aLength, bLength)
            let last := add(add(result, 0x20), totalLength)
        // Zeroize the slot after the string.
            mstore(last, 0)
        // Stores the length.
            mstore(result, totalLength)
        // Allocate memory for the length and the bytes,
        // rounded up to a multiple of 32.
            mstore(0x40, and(add(last, 0x1f), w))
        }
    }

    /// @dev Returns a copy of the string in either lowercase or UPPERCASE.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function toCase(string memory subject, bool toUpper)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let length := mload(subject)
            if length {
                result := add(mload(0x40), 0x20)
                subject := add(subject, 1)
                let flags := shl(add(70, shl(5, toUpper)), 0x3ffffff)
                let w := not(0)
                for { let o := length } 1 {} {
                    o := add(o, w)
                    let b := and(0xff, mload(add(subject, o)))
                    mstore8(add(result, o), xor(b, and(shr(b, flags), 0x20)))
                    if iszero(o) { break }
                }
                result := mload(0x40)
                mstore(result, length) // Store the length.
                let last := add(add(result, 0x20), length)
                mstore(last, 0) // Zeroize the slot after the string.
                mstore(0x40, add(last, 0x20)) // Allocate the memory.
            }
        }
    }

    /// @dev Returns a string from a small bytes32 string.
    /// `s` must be null-terminated, or behavior will be undefined.
    function fromSmallString(bytes32 s) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            let n := 0
            for {} byte(n, s) { n := add(n, 1) } {} // Scan for '\0'.
            mstore(result, n)
            let o := add(result, 0x20)
            mstore(o, s)
            mstore(add(o, n), 0)
            mstore(0x40, add(result, 0x40))
        }
    }

    /// @dev Returns the small string, with all bytes after the first null byte zeroized.
    function normalizeSmallString(bytes32 s) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            for {} byte(result, s) { result := add(result, 1) } {} // Scan for '\0'.
            mstore(0x00, s)
            mstore(result, 0x00)
            result := mload(0x00)
        }
    }

    /// @dev Returns the string as a normalized null-terminated small string.
    function toSmallString(string memory s) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(s)
            if iszero(lt(result, 33)) {
                mstore(0x00, 0xec92f9a3) // `TooBigForSmallString()`.
                revert(0x1c, 0x04)
            }
            result := shl(shl(3, sub(32, result)), mload(add(s, result)))
        }
    }

    /// @dev Returns a lowercased copy of the string.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function lower(string memory subject) internal pure returns (string memory result) {
        result = toCase(subject, false);
    }

    /// @dev Returns an UPPERCASED copy of the string.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function upper(string memory subject) internal pure returns (string memory result) {
        result = toCase(subject, true);
    }

    /// @dev Escapes the string to be used within HTML tags.
    function escapeHTML(string memory s) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            let end := add(s, mload(s))
            result := add(mload(0x40), 0x20)
        // Store the bytes of the packed offsets and strides into the scratch space.
        // `packed = (stride << 5) | offset`. Max offset is 20. Max stride is 6.
            mstore(0x1f, 0x900094)
            mstore(0x08, 0xc0000000a6ab)
        // Store "&quot;&amp;&#39;&lt;&gt;" into the scratch space.
            mstore(0x00, shl(64, 0x2671756f743b26616d703b262333393b266c743b2667743b))
            for {} iszero(eq(s, end)) {} {
                s := add(s, 1)
                let c := and(mload(s), 0xff)
            // Not in `["\"","'","&","<",">"]`.
                if iszero(and(shl(c, 1), 0x500000c400000000)) {
                    mstore8(result, c)
                    result := add(result, 1)
                    continue
                }
                let t := shr(248, mload(c))
                mstore(result, mload(and(t, 0x1f)))
                result := add(result, shr(5, t))
            }
            let last := result
            mstore(last, 0) // Zeroize the slot after the string.
            result := mload(0x40)
            mstore(result, sub(last, add(result, 0x20))) // Store the length.
            mstore(0x40, add(last, 0x20)) // Allocate the memory.
        }
    }

    /// @dev Escapes the string to be used within double-quotes in a JSON.
    /// If `addDoubleQuotes` is true, the result will be enclosed in double-quotes.
    function escapeJSON(string memory s, bool addDoubleQuotes)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let end := add(s, mload(s))
            result := add(mload(0x40), 0x20)
            if addDoubleQuotes {
                mstore8(result, 34)
                result := add(1, result)
            }
        // Store "\\u0000" in scratch space.
        // Store "0123456789abcdef" in scratch space.
        // Also, store `{0x08:"b", 0x09:"t", 0x0a:"n", 0x0c:"f", 0x0d:"r"}`.
        // into the scratch space.
            mstore(0x15, 0x5c75303030303031323334353637383961626364656662746e006672)
        // Bitmask for detecting `["\"","\\"]`.
            let e := or(shl(0x22, 1), shl(0x5c, 1))
            for {} iszero(eq(s, end)) {} {
                s := add(s, 1)
                let c := and(mload(s), 0xff)
                if iszero(lt(c, 0x20)) {
                    if iszero(and(shl(c, 1), e)) {
                    // Not in `["\"","\\"]`.
                        mstore8(result, c)
                        result := add(result, 1)
                        continue
                    }
                    mstore8(result, 0x5c) // "\\".
                    mstore8(add(result, 1), c)
                    result := add(result, 2)
                    continue
                }
                if iszero(and(shl(c, 1), 0x3700)) {
                // Not in `["\b","\t","\n","\f","\d"]`.
                    mstore8(0x1d, mload(shr(4, c))) // Hex value.
                    mstore8(0x1e, mload(and(c, 15))) // Hex value.
                    mstore(result, mload(0x19)) // "\\u00XX".
                    result := add(result, 6)
                    continue
                }
                mstore8(result, 0x5c) // "\\".
                mstore8(add(result, 1), mload(add(c, 8)))
                result := add(result, 2)
            }
            if addDoubleQuotes {
                mstore8(result, 34)
                result := add(1, result)
            }
            let last := result
            mstore(last, 0) // Zeroize the slot after the string.
            result := mload(0x40)
            mstore(result, sub(last, add(result, 0x20))) // Store the length.
            mstore(0x40, add(last, 0x20)) // Allocate the memory.
        }
    }

    /// @dev Escapes the string to be used within double-quotes in a JSON.
    function escapeJSON(string memory s) internal pure returns (string memory result) {
        result = escapeJSON(s, false);
    }

    /// @dev Returns whether `a` equals `b`.
    function eq(string memory a, string memory b) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := eq(keccak256(add(a, 0x20), mload(a)), keccak256(add(b, 0x20), mload(b)))
        }
    }

    /// @dev Returns whether `a` equals `b`, where `b` is a null-terminated small string.
    function eqs(string memory a, bytes32 b) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
        // These should be evaluated on compile time, as far as possible.
            let m := not(shl(7, div(not(iszero(b)), 255))) // `0x7f7f ...`.
            let x := not(or(m, or(b, add(m, and(b, m)))))
            let r := shl(7, iszero(iszero(shr(128, x))))
            r := or(r, shl(6, iszero(iszero(shr(64, shr(r, x))))))
            r := or(r, shl(5, lt(0xffffffff, shr(r, x))))
            r := or(r, shl(4, lt(0xffff, shr(r, x))))
            r := or(r, shl(3, lt(0xff, shr(r, x))))
        // forgefmt: disable-next-item
            result := gt(eq(mload(a), add(iszero(x), xor(31, shr(3, r)))),
                xor(shr(add(8, r), b), shr(add(8, r), mload(add(a, 0x20)))))
        }
    }

    /// @dev Packs a single string with its length into a single word.
    /// Returns `bytes32(0)` if the length is zero or greater than 31.
    function packOne(string memory a) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
        // We don't need to zero right pad the string,
        // since this is our own custom non-standard packing scheme.
            result :=
            mul(
            // Load the length and the bytes.
                mload(add(a, 0x1f)),
            // `length != 0 && length < 32`. Abuses underflow.
            // Assumes that the length is valid and within the block gas limit.
                lt(sub(mload(a), 1), 0x1f)
            )
        }
    }

    /// @dev Unpacks a string packed using {packOne}.
    /// Returns the empty string if `packed` is `bytes32(0)`.
    /// If `packed` is not an output of {packOne}, the output behavior is undefined.
    function unpackOne(bytes32 packed) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
        // Grab the free memory pointer.
            result := mload(0x40)
        // Allocate 2 words (1 for the length, 1 for the bytes).
            mstore(0x40, add(result, 0x40))
        // Zeroize the length slot.
            mstore(result, 0)
        // Store the length and bytes.
            mstore(add(result, 0x1f), packed)
        // Right pad with zeroes.
            mstore(add(add(result, 0x20), mload(result)), 0)
        }
    }

    /// @dev Packs two strings with their lengths into a single word.
    /// Returns `bytes32(0)` if combined length is zero or greater than 30.
    function packTwo(string memory a, string memory b) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            let aLength := mload(a)
        // We don't need to zero right pad the strings,
        // since this is our own custom non-standard packing scheme.
            result :=
            mul(
            // Load the length and the bytes of `a` and `b`.
                or(
                    shl(shl(3, sub(0x1f, aLength)), mload(add(a, aLength))),
                    mload(sub(add(b, 0x1e), aLength))
                ),
            // `totalLength != 0 && totalLength < 31`. Abuses underflow.
            // Assumes that the lengths are valid and within the block gas limit.
                lt(sub(add(aLength, mload(b)), 1), 0x1e)
            )
        }
    }

    /// @dev Unpacks strings packed using {packTwo}.
    /// Returns the empty strings if `packed` is `bytes32(0)`.
    /// If `packed` is not an output of {packTwo}, the output behavior is undefined.
    function unpackTwo(bytes32 packed)
    internal
    pure
    returns (string memory resultA, string memory resultB)
    {
        /// @solidity memory-safe-assembly
        assembly {
        // Grab the free memory pointer.
            resultA := mload(0x40)
            resultB := add(resultA, 0x40)
        // Allocate 2 words for each string (1 for the length, 1 for the byte). Total 4 words.
            mstore(0x40, add(resultB, 0x40))
        // Zeroize the length slots.
            mstore(resultA, 0)
            mstore(resultB, 0)
        // Store the lengths and bytes.
            mstore(add(resultA, 0x1f), packed)
            mstore(add(resultB, 0x1f), mload(add(add(resultA, 0x20), mload(resultA))))
        // Right pad with zeroes.
            mstore(add(add(resultA, 0x20), mload(resultA)), 0)
            mstore(add(add(resultB, 0x20), mload(resultB)), 0)
        }
    }

    /// @dev Directly returns `a` without copying.
    function directReturn(string memory a) internal pure {
        assembly {
        // Assumes that the string does not start from the scratch space.
            let retStart := sub(a, 0x20)
            let retSize := add(mload(a), 0x40)
        // Right pad with zeroes. Just in case the string is produced
        // by a method that doesn't zero right pad.
            mstore(add(retStart, retSize), 0)
        // Store the return offset.
            mstore(retStart, 0x20)
        // End the transaction, returning the string.
            return(retStart, retSize)
        }
    }
}

/// @notice Simple single owner authorization mixin.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/auth/Ownable.sol)
///
/// @dev Note:
/// This implementation does NOT auto-initialize the owner to `msg.sender`.
/// You MUST call the `_initializeOwner` in the constructor / initializer.
///
/// While the ownable portion follows
/// [EIP-173](https://eips.ethereum.org/EIPS/eip-173) for compatibility,
/// the nomenclature for the 2-step ownership handover may be unique to this codebase.
abstract contract Ownable {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                       CUSTOM ERRORS                        */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The caller is not authorized to call the function.
    error Unauthorized();

    /// @dev The `newOwner` cannot be the zero address.
    error NewOwnerIsZeroAddress();

    /// @dev The `pendingOwner` does not have a valid handover request.
    error NoHandoverRequest();

    /// @dev Cannot double-initialize.
    error AlreadyInitialized();

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                           EVENTS                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The ownership is transferred from `oldOwner` to `newOwner`.
    /// This event is intentionally kept the same as OpenZeppelin's Ownable to be
    /// compatible with indexers and [EIP-173](https://eips.ethereum.org/EIPS/eip-173),
    /// despite it not being as lightweight as a single argument event.
    event OwnershipTransferred(address indexed oldOwner, address indexed newOwner);

    /// @dev An ownership handover to `pendingOwner` has been requested.
    event OwnershipHandoverRequested(address indexed pendingOwner);

    /// @dev The ownership handover to `pendingOwner` has been canceled.
    event OwnershipHandoverCanceled(address indexed pendingOwner);

    /// @dev `keccak256(bytes("OwnershipTransferred(address,address)"))`.
    uint256 private constant _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE =
    0x8be0079c531659141344cd1fd0a4f28419497f9722a3daafe3b4186f6b6457e0;

    /// @dev `keccak256(bytes("OwnershipHandoverRequested(address)"))`.
    uint256 private constant _OWNERSHIP_HANDOVER_REQUESTED_EVENT_SIGNATURE =
    0xdbf36a107da19e49527a7176a1babf963b4b0ff8cde35ee35d6cd8f1f9ac7e1d;

    /// @dev `keccak256(bytes("OwnershipHandoverCanceled(address)"))`.
    uint256 private constant _OWNERSHIP_HANDOVER_CANCELED_EVENT_SIGNATURE =
    0xfa7b8eab7da67f412cc9575ed43464468f9bfbae89d1675917346ca6d8fe3c92;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                          STORAGE                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The owner slot is given by:
    /// `bytes32(~uint256(uint32(bytes4(keccak256("_OWNER_SLOT_NOT")))))`.
    /// It is intentionally chosen to be a high value
    /// to avoid collision with lower slots.
    /// The choice of manual storage layout is to enable compatibility
    /// with both regular and upgradeable contracts.
    bytes32 internal constant _OWNER_SLOT =
    0xffffffffffffffffffffffffffffffffffffffffffffffffffffffff74873927;

    /// The ownership handover slot of `newOwner` is given by:
    /// ```
    ///     mstore(0x00, or(shl(96, user), _HANDOVER_SLOT_SEED))
    ///     let handoverSlot := keccak256(0x00, 0x20)
    /// ```
    /// It stores the expiry timestamp of the two-step ownership handover.
    uint256 private constant _HANDOVER_SLOT_SEED = 0x389a75e1;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     INTERNAL FUNCTIONS                     */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Override to return true to make `_initializeOwner` prevent double-initialization.
    function _guardInitializeOwner() internal pure virtual returns (bool guard) {}

    /// @dev Initializes the owner directly without authorization guard.
    /// This function must be called upon initialization,
    /// regardless of whether the contract is upgradeable or not.
    /// This is to enable generalization to both regular and upgradeable contracts,
    /// and to save gas in case the initial owner is not the caller.
    /// For performance reasons, this function will not check if there
    /// is an existing owner.
    function _initializeOwner(address newOwner) internal virtual {
        if (_guardInitializeOwner()) {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
                if sload(ownerSlot) {
                    mstore(0x00, 0x0dc149f0) // `AlreadyInitialized()`.
                    revert(0x1c, 0x04)
                }
            // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
            // Store the new value.
                sstore(ownerSlot, or(newOwner, shl(255, iszero(newOwner))))
            // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, 0, newOwner)
            }
        } else {
            /// @solidity memory-safe-assembly
            assembly {
            // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
            // Store the new value.
                sstore(_OWNER_SLOT, newOwner)
            // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, 0, newOwner)
            }
        }
    }

    /// @dev Sets the owner directly without authorization guard.
    function _setOwner(address newOwner) internal virtual {
        if (_guardInitializeOwner()) {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
            // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
            // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, sload(ownerSlot), newOwner)
            // Store the new value.
                sstore(ownerSlot, or(newOwner, shl(255, iszero(newOwner))))
            }
        } else {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
            // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
            // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, sload(ownerSlot), newOwner)
            // Store the new value.
                sstore(ownerSlot, newOwner)
            }
        }
    }

    /// @dev Throws if the sender is not the owner.
    function _checkOwner() internal view virtual {
        /// @solidity memory-safe-assembly
        assembly {
        // If the caller is not the stored owner, revert.
            if iszero(eq(caller(), sload(_OWNER_SLOT))) {
                mstore(0x00, 0x82b42900) // `Unauthorized()`.
                revert(0x1c, 0x04)
            }
        }
    }

    /// @dev Returns how long a two-step ownership handover is valid for in seconds.
    /// Override to return a different value if needed.
    /// Made internal to conserve bytecode. Wrap it in a public function if needed.
    function _ownershipHandoverValidFor() internal view virtual returns (uint64) {
        return 48 * 3600;
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  PUBLIC UPDATE FUNCTIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Allows the owner to transfer the ownership to `newOwner`.
    function transferOwnership(address newOwner) public payable virtual onlyOwner {
        /// @solidity memory-safe-assembly
        assembly {
            if iszero(shl(96, newOwner)) {
                mstore(0x00, 0x7448fbae) // `NewOwnerIsZeroAddress()`.
                revert(0x1c, 0x04)
            }
        }
        _setOwner(newOwner);
    }

    /// @dev Allows the owner to renounce their ownership.
    function renounceOwnership() public payable virtual onlyOwner {
        _setOwner(address(0));
    }

    /// @dev Request a two-step ownership handover to the caller.
    /// The request will automatically expire in 48 hours (172800 seconds) by default.
    function requestOwnershipHandover() public payable virtual {
        unchecked {
            uint256 expires = block.timestamp + _ownershipHandoverValidFor();
        /// @solidity memory-safe-assembly
            assembly {
            // Compute and set the handover slot to `expires`.
                mstore(0x0c, _HANDOVER_SLOT_SEED)
                mstore(0x00, caller())
                sstore(keccak256(0x0c, 0x20), expires)
            // Emit the {OwnershipHandoverRequested} event.
                log2(0, 0, _OWNERSHIP_HANDOVER_REQUESTED_EVENT_SIGNATURE, caller())
            }
        }
    }

    /// @dev Cancels the two-step ownership handover to the caller, if any.
    function cancelOwnershipHandover() public payable virtual {
        /// @solidity memory-safe-assembly
        assembly {
        // Compute and set the handover slot to 0.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, caller())
            sstore(keccak256(0x0c, 0x20), 0)
        // Emit the {OwnershipHandoverCanceled} event.
            log2(0, 0, _OWNERSHIP_HANDOVER_CANCELED_EVENT_SIGNATURE, caller())
        }
    }

    /// @dev Allows the owner to complete the two-step ownership handover to `pendingOwner`.
    /// Reverts if there is no existing ownership handover requested by `pendingOwner`.
    function completeOwnershipHandover(address pendingOwner) public payable virtual onlyOwner {
        /// @solidity memory-safe-assembly
        assembly {
        // Compute and set the handover slot to 0.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, pendingOwner)
            let handoverSlot := keccak256(0x0c, 0x20)
        // If the handover does not exist, or has expired.
            if gt(timestamp(), sload(handoverSlot)) {
                mstore(0x00, 0x6f5e8818) // `NoHandoverRequest()`.
                revert(0x1c, 0x04)
            }
        // Set the handover slot to 0.
            sstore(handoverSlot, 0)
        }
        _setOwner(pendingOwner);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   PUBLIC READ FUNCTIONS                    */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the owner of the contract.
    function owner() public view virtual returns (address result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := sload(_OWNER_SLOT)
        }
    }

    /// @dev Returns the expiry timestamp for the two-step ownership handover to `pendingOwner`.
    function ownershipHandoverExpiresAt(address pendingOwner)
    public
    view
    virtual
    returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
        // Compute the handover slot.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, pendingOwner)
        // Load the handover slot.
            result := sload(keccak256(0x0c, 0x20))
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         MODIFIERS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Marks a function as only callable by the owner.
    modifier onlyOwner() virtual {
        _checkOwner();
        _;
    }
}


/// @title ERC_YB_NFT
/// @notice ERC_YB_NFT provides an interface for interacting with the
/// NFT tokens in a DN404 implementation.
///
/// @author vectorized.eth (@optimizoor)
/// @author Quit (@0xQuit)
/// @author Michael Amadi (@AmadiMichaels)
/// @author cygaar (@0xCygaar)
/// @author Thomas (@0xjustadev)
/// @author Harrison (@PopPunkOnChain)
///
/// @dev Note:
/// - The ERC721 data is stored in the base DN404 contract.
contract ERC_YB_NFT {
    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                           EVENTS                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Emitted when token `id` is transferred from `from` to `to`.
    event Transfer(address indexed from, address indexed to, uint256 indexed id);

    /// @dev Emitted when `owner` enables `account` to manage the `id` token.
    event Approval(address indexed owner, address indexed account, uint256 indexed id);

    /// @dev Emitted when `owner` enables or disables `operator` to manage all of their tokens.
    event ApprovalForAll(address indexed owner, address indexed operator, bool isApproved);

    /// @dev The ownership is transferred from `oldOwner` to `newOwner`.
    /// This is for marketplace signaling purposes. This contract has a `pullOwner()`
    /// function that will sync the owner from the base contract.
    event OwnershipTransferred(address indexed oldOwner, address indexed newOwner);

    /// @dev `keccak256(bytes("Transfer(address,address,uint256)"))`.
    uint256 private constant _TRANSFER_EVENT_SIGNATURE =
    0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

    /// @dev `keccak256(bytes("Approval(address,address,uint256)"))`.
    uint256 private constant _APPROVAL_EVENT_SIGNATURE =
    0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925;

    /// @dev `keccak256(bytes("ApprovalForAll(address,address,bool)"))`.
    uint256 private constant _APPROVAL_FOR_ALL_EVENT_SIGNATURE =
    0x17307eab39ab6107e8899845ad3d59bd9653f200f220920489ca2b5937696c31;

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CUSTOM ERRORS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Thrown when a call for an NFT function did not originate
    /// from the base DN404 contract.
    error SenderNotBase();

    /// @dev Thrown when a call for an NFT function did not originate from the deployer.
    error SenderNotDeployer();

    /// @dev Thrown when transferring an NFT to a contract address that
    /// does not implement ERC721Receiver.
    error TransferToNonERC721ReceiverImplementer();

    /// @dev Thrown when linking to the DN404 base contract and the
    /// DN404 supportsInterface check fails or the call reverts.
    error CannotLink();

    /// @dev Thrown when a linkMirrorContract call is received and the
    /// NFT mirror contract has already been linked to a DN404 base contract.
    error AlreadyLinked();

    /// @dev Thrown when retrieving the base DN404 address when a link has not
    /// been established.
    error NotLinked();

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                          STORAGE                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Struct contain the NFT mirror contract storage.
    struct DN404NFTStorage {
        address baseERC20;
        address deployer;
        address owner;
    }

    /// @dev Returns a storage pointer for DN404NFTStorage.
    function _getDN404NFTStorage() internal pure virtual returns (DN404NFTStorage storage $) {
        /// @solidity memory-safe-assembly
        assembly {
        // `uint72(bytes9(keccak256("DN404_MIRROR_STORAGE")))`.
            $.slot := 0x3602298b8c10b01230 // Truncate to 9 bytes to reduce bytecode size.
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CONSTRUCTOR                         */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    constructor(address deployer) {
        // For non-proxies, we will store the deployer so that only the deployer can
        // link the base contract.
        _getDN404NFTStorage().deployer = deployer;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     ERC721 OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the token collection name from the base DN404 contract.
    function name() public view virtual returns (string memory result) {
        return _readString(0x06fdde03, 0); // `symbol()`.
    }

    /// @dev Returns the token collection symbol from the base DN404 contract.
    function symbol() public view virtual returns (string memory result) {
        return _readString(0x95d89b41, 0); // `symbol()`.
    }

    /// @dev Returns the Uniform Resource Identifier (URI) for token `id` from
    /// the base DN404 contract.
    function tokenURI(uint256 id) public view virtual returns (string memory result) {
        return _readString(0xc87b56dd, id); // `tokenURI()`.
    }

    /// @dev Returns the total NFT supply from the base DN404 contract.
    function totalSupply() public view virtual returns (uint256 result) {
        return _readWord(0xe2c79281, 0, 0); // `totalNFTSupply()`.
    }

    /// @dev Returns the number of NFT tokens owned by `nftOwner` from the base DN404 contract.
    ///
    /// Requirements:
    /// - `nftOwner` must not be the zero address.
    function balanceOf(address nftOwner) public view virtual returns (uint256 result) {
        return _readWord(0xf5b100ea, uint160(nftOwner), 0); // `balanceOfNFT(address)`.
    }

    /// @dev Returns the owner of token `id` from the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function ownerOf(uint256 id) public view virtual returns (address result) {
        return address(uint160(_readWord(0x6352211e, id, 0))); // `ownerOf(uint256)`.
    }

    /// @dev Returns the owner of token `id` from the base DN404 contract.
    /// Returns `address(0)` instead of reverting if the token does not exist.
    function ownerAt(uint256 id) public view virtual returns (address result) {
        return address(uint160(_readWord(0x24359879, id, 0))); // `ownerAt(uint256)`.
    }

    /// @dev Sets `spender` as the approved account to manage token `id` in
    /// the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    /// - The caller must be the owner of the token,
    ///   or an approved operator for the token owner.
    ///
    /// Emits an {Approval} event.
    function approve(address spender, uint256 id) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            spender := shr(96, shl(96, spender))
            let m := mload(0x40)
            mstore(0x00, 0xd10b6e0c) // `approveNFT(address,uint256,address)`.
            mstore(0x20, spender)
            mstore(0x40, id)
            mstore(0x60, caller())
            if iszero(
                and(
                    gt(returndatasize(), 0x1f),
                    call(gas(), base, callvalue(), 0x1c, 0x64, 0x00, 0x20)
                )
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
            mstore(0x40, m) // Restore the free memory pointer.
            mstore(0x60, 0) // Restore the zero pointer.
        // Emit the {Approval} event.
            log4(codesize(), 0x00, _APPROVAL_EVENT_SIGNATURE, shr(96, mload(0x0c)), spender, id)
        }
    }

    /// @dev Returns the account approved to manage token `id` from
    /// the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function getApproved(uint256 id) public view virtual returns (address) {
        return address(uint160(_readWord(0x081812fc, id, 0))); // `getApproved(uint256)`.
    }

    /// @dev Sets whether `operator` is approved to manage the tokens of the caller in
    /// the base DN404 contract.
    ///
    /// Emits an {ApprovalForAll} event.
    function setApprovalForAll(address operator, bool approved) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            operator := shr(96, shl(96, operator))
            let m := mload(0x40)
            mstore(0x00, 0x813500fc) // `setApprovalForAll(address,bool,address)`.
            mstore(0x20, operator)
            mstore(0x40, iszero(iszero(approved)))
            mstore(0x60, caller())
            if iszero(
                and(eq(mload(0x00), 1), call(gas(), base, callvalue(), 0x1c, 0x64, 0x00, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
        // Emit the {ApprovalForAll} event.
        // The `approved` value is already at 0x40.
            log3(0x40, 0x20, _APPROVAL_FOR_ALL_EVENT_SIGNATURE, caller(), operator)
            mstore(0x40, m) // Restore the free memory pointer.
            mstore(0x60, 0) // Restore the zero pointer.
        }
    }

    /// @dev Returns whether `operator` is approved to manage the tokens of `nftOwner` from
    /// the base DN404 contract.
    function isApprovedForAll(address nftOwner, address operator)
    public
    view
    virtual
    returns (bool result)
    {
        // `isApprovedForAll(address,address)`.
        return _readWord(0xe985e9c5, uint160(nftOwner), uint160(operator)) != 0;
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function transferFrom(address from, address to, uint256 id) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            from := shr(96, shl(96, from))
            to := shr(96, shl(96, to))
            let m := mload(0x40)
            mstore(m, 0xe5eb36c8) // `transferFromNFT(address,address,uint256,address)`.
            mstore(add(m, 0x20), from)
            mstore(add(m, 0x40), to)
            mstore(add(m, 0x60), id)
            mstore(add(m, 0x80), caller())
            if iszero(
                and(eq(mload(m), 1), call(gas(), base, callvalue(), add(m, 0x1c), 0x84, m, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
        // Emit the {Transfer} event.
            log4(codesize(), 0x00, _TRANSFER_EVENT_SIGNATURE, from, to, id)
        }
    }

    /// @dev Equivalent to `safeTransferFrom(from, to, id, "")`.
    function safeTransferFrom(address from, address to, uint256 id) public payable virtual {
        transferFrom(from, to, id);

        if (_hasCode(to)) _checkOnERC721Received(from, to, id, "");
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    /// - If `to` refers to a smart contract, it must implement
    ///   {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
    ///
    /// Emits a {Transfer} event.
    function safeTransferFrom(address from, address to, uint256 id, bytes calldata data)
    public
    virtual
    {
        transferFrom(from, to, id);

        if (_hasCode(to)) _checkOnERC721Received(from, to, id, data);
    }

    /// @dev Returns true if this contract implements the interface defined by `interfaceId`.
    /// See: https://eips.ethereum.org/EIPS/eip-165
    /// This function call must use less than 30000 gas.
    function supportsInterface(bytes4 interfaceId) public view virtual returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            let s := shr(224, interfaceId)
        // ERC165: 0x01ffc9a7, ERC721: 0x80ac58cd, ERC721Metadata: 0x5b5e139f.
            result := or(or(eq(s, 0x01ffc9a7), eq(s, 0x80ac58cd)), eq(s, 0x5b5e139f))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                  OWNER SYNCING OPERATIONS                  */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the `owner` of the contract, for marketplace signaling purposes.
    function owner() public view virtual returns (address) {
        return _getDN404NFTStorage().owner;
    }

    /// @dev Permissionless function to pull the owner from the base DN404 contract
    /// if it implements ownable, for marketplace signaling purposes.
    function pullOwner() public virtual {
        address newOwner;
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, 0x8da5cb5b) // `owner()`.
            if and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x04, 0x00, 0x20)) {
                newOwner := shr(96, mload(0x0c))
            }
        }
        DN404NFTStorage storage $ = _getDN404NFTStorage();
        address oldOwner = $.owner;
        if (oldOwner != newOwner) {
            $.owner = newOwner;
            emit OwnershipTransferred(oldOwner, newOwner);
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     MIRROR OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the address of the base DN404 contract.
    function baseERC20() public view virtual returns (address base) {
        base = _getDN404NFTStorage().baseERC20;
        if (base == address(0)) revert NotLinked();
    }

    /// @dev Fallback modifier to execute calls from the base DN404 contract.
    modifier dn404NFTFallback() virtual {
        DN404NFTStorage storage $ = _getDN404NFTStorage();

        uint256 fnSelector = _calldataload(0x00) >> 224;

        // `logTransfer(uint256[])`.
        if (fnSelector == 0x263c69d6) {
            if (msg.sender != $.baseERC20) revert SenderNotBase();
            /// @solidity memory-safe-assembly
            assembly {
            // When returndatacopy copies 1 or more out-of-bounds bytes, it reverts.
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), 0x20))
                let o := add(0x24, calldataload(0x04)) // Packed logs offset.
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), o))
                let end := add(o, shl(5, calldataload(sub(o, 0x20))))
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), end))

                for {} iszero(eq(o, end)) { o := add(0x20, o) } {
                    let d := calldataload(o) // Entry in the packed logs.
                    let a := shr(96, d) // The address.
                    let b := and(1, d) // Whether it is a burn.
                    log4(
                        codesize(),
                        0x00,
                        _TRANSFER_EVENT_SIGNATURE,
                        mul(a, b), // `from`.
                        mul(a, iszero(b)), // `to`.
                        shr(168, shl(160, d)) // `id`.
                    )
                }
                mstore(0x00, 0x01)
                return(0x00, 0x20)
            }
        }
        // `linkMirrorContract(address)`.
        if (fnSelector == 0x0f4599e5) {
            if ($.deployer != address(0)) {
                if (address(uint160(_calldataload(0x04))) != $.deployer) {
                    revert SenderNotDeployer();
                }
            }
            if ($.baseERC20 != address(0)) revert AlreadyLinked();
            $.baseERC20 = msg.sender;
            /// @solidity memory-safe-assembly
            assembly {
                mstore(0x00, 0x01)
                return(0x00, 0x20)
            }
        }
        _;
    }

    /// @dev Fallback function for calls from base DN404 contract.
    fallback() external payable virtual dn404NFTFallback {}

    receive() external payable virtual {}

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                      PRIVATE HELPERS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Helper to read a string from the base DN404 contract.
    function _readString(uint256 fnSelector, uint256 arg0)
    private
    view
    returns (string memory result)
    {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            mstore(0x00, fnSelector)
            mstore(0x20, arg0)
            if iszero(staticcall(gas(), base, 0x1c, 0x24, 0x00, 0x00)) {
                returndatacopy(result, 0x00, returndatasize())
                revert(result, returndatasize())
            }
            returndatacopy(0x00, 0x00, 0x20) // Copy the offset of the string in returndata.
            returndatacopy(result, mload(0x00), 0x20) // Copy the length of the string.
            returndatacopy(add(result, 0x20), add(mload(0x00), 0x20), mload(result)) // Copy the string.
            mstore(0x40, add(add(result, 0x20), mload(result))) // Allocate memory.
        }
    }

    /// @dev Helper to read a word from the base DN404 contract.
    function _readWord(uint256 fnSelector, uint256 arg0, uint256 arg1)
    private
    view
    returns (uint256 result)
    {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            mstore(0x00, fnSelector)
            mstore(0x20, arg0)
            mstore(0x40, arg1)
            if iszero(
                and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x44, 0x00, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
            mstore(0x40, m) // Restore the free memory pointer.
            result := mload(0x00)
        }
    }

    /// @dev Returns the calldata value at `offset`.
    function _calldataload(uint256 offset) private pure returns (uint256 value) {
        /// @solidity memory-safe-assembly
        assembly {
            value := calldataload(offset)
        }
    }

    /// @dev Returns if `a` has bytecode of non-zero length.
    function _hasCode(address a) private view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := extcodesize(a) // Can handle dirty upper bits.
        }
    }

    /// @dev Perform a call to invoke {IERC721Receiver-onERC721Received} on `to`.
    /// Reverts if the target does not support the function correctly.
    function _checkOnERC721Received(address from, address to, uint256 id, bytes memory data)
    private
    {
        /// @solidity memory-safe-assembly
        assembly {
        // Prepare the calldata.
            let m := mload(0x40)
            let onERC721ReceivedSelector := 0x150b7a02
            mstore(m, onERC721ReceivedSelector)
            mstore(add(m, 0x20), caller()) // The `operator`, which is always `msg.sender`.
            mstore(add(m, 0x40), shr(96, shl(96, from)))
            mstore(add(m, 0x60), id)
            mstore(add(m, 0x80), 0x80)
            let n := mload(data)
            mstore(add(m, 0xa0), n)
            if n { pop(staticcall(gas(), 4, add(data, 0x20), n, add(m, 0xc0), n)) }
        // Revert if the call reverts.
            if iszero(call(gas(), to, 0, add(m, 0x1c), add(n, 0xa4), m, 0x20)) {
                if returndatasize() {
                // Bubble up the revert if the call reverts.
                    returndatacopy(m, 0x00, returndatasize())
                    revert(m, returndatasize())
                }
            }
        // Load the returndata and compare it.
            if iszero(eq(mload(m), shl(224, onERC721ReceivedSelector))) {
                mstore(0x00, 0xd1a57ed6) // `TransferToNonERC721ReceiverImplementer()`.
                revert(0x1c, 0x04)
            }
        }
    }
}

/// @title DN404
/// @notice DN404 is a hybrid ERC20 and ERC721 implementation that mints
/// and burns NFTs based on an account's ERC20 token balance.
///
/// @author vectorized.eth (@optimizoor)
/// @author Quit (@0xQuit)
/// @author Michael Amadi (@AmadiMichaels)
/// @author cygaar (@0xCygaar)
/// @author Thomas (@0xjustadev)
/// @author Harrison (@PopPunkOnChain)
///
/// @dev Note:
/// - The ERC721 data is stored in this base DN404 contract, however a
///   ERC_YB_NFT contract ***MUST*** be deployed and linked during
///   initialization.
abstract contract ERC_YB {
    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                           EVENTS                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Emitted when `amount` tokens is transferred from `from` to `to`.
    event Transfer(address indexed from, address indexed to, uint256 amount);

    /// @dev Emitted when `amount` tokens is approved by `owner` to be used by `spender`.
    event Approval(address indexed owner, address indexed spender, uint256 amount);

    /// @dev Emitted when `target` sets their skipNFT flag to `status`.
    event SkipNFTSet(address indexed target, bool status);

    /// @dev `keccak256(bytes("Transfer(address,address,uint256)"))`.
    uint256 private constant _TRANSFER_EVENT_SIGNATURE =
    0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

    /// @dev `keccak256(bytes("Approval(address,address,uint256)"))`.
    uint256 private constant _APPROVAL_EVENT_SIGNATURE =
    0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925;

    /// @dev `keccak256(bytes("SkipNFTSet(address,bool)"))`.
    uint256 private constant _SKIP_NFT_SET_EVENT_SIGNATURE =
    0xb5a1de456fff688115a4f75380060c23c8532d14ff85f687cc871456d6420393;

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CUSTOM ERRORS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Thrown when attempting to double-initialize the contract.
    error DNAlreadyInitialized();

    /// @dev Thrown when attempting to transfer or burn more tokens than sender's balance.
    error InsufficientBalance();

    /// @dev Thrown when a spender attempts to transfer tokens with an insufficient allowance.
    error InsufficientAllowance();

    /// @dev Thrown when minting an amount of tokens that would overflow the max tokens.
    error TotalSupplyOverflow();

    /// @dev The unit cannot be zero.
    error UnitIsZero();

    /// @dev Thrown when the caller for a fallback NFT function is not the mirror contract.
    error SenderNotMirror();

    /// @dev Thrown when attempting to transfer tokens to the zero address.
    error TransferToZeroAddress();

    /// @dev Thrown when the mirror address provided for initialization is the zero address.
    error MirrorAddressIsZero();

    /// @dev Thrown when the link call to the mirror contract reverts.
    error LinkMirrorContractFailed();

    /// @dev Thrown when setting an NFT token approval
    /// and the caller is not the owner or an approved operator.
    error ApprovalCallerNotOwnerNorApproved();

    /// @dev Thrown when transferring an NFT
    /// and the caller is not the owner or an approved operator.
    error TransferCallerNotOwnerNorApproved();

    /// @dev Thrown when transferring an NFT and the from address is not the current owner.
    error TransferFromIncorrectOwner();

    /// @dev Thrown when checking the owner or approved address for a non-existent NFT.
    error TokenDoesNotExist();

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                         CONSTANTS                          */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev The flag to denote that the address data is initialized.
    uint8 internal constant _ADDRESS_DATA_INITIALIZED_FLAG = 1 << 0;

    /// @dev The flag to denote that the address should skip NFTs.
    uint8 internal constant _ADDRESS_DATA_SKIP_NFT_FLAG = 1 << 1;

    /// @dev The flag to denote that the address has overridden the default Permit2 allowance.
    uint8 internal constant _ADDRESS_DATA_OVERRIDE_PERMIT2_FLAG = 1 << 2;

    /// @dev The canonical Permit2 address.
    /// For signature-based allowance granting for single transaction ERC20 `transferFrom`.
    /// To enable, override `_givePermit2DefaultInfiniteAllowance()`.
    /// [Github](https://github.com/Uniswap/permit2)
    /// [Etherscan](https://etherscan.io/address/0x000000000022D473030F116dDEE9F6B43aC78BA3)
    address internal constant _PERMIT2 = 0x000000000022D473030F116dDEE9F6B43aC78BA3;

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                          STORAGE                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Struct containing an address's token data and settings.
    struct AddressData {
        // Auxiliary data.
        uint88 aux;
        // Flags for `initialized` and `skipNFT`.
        uint8 flags;
        // The alias for the address. Zero means absence of an alias.
        uint32 addressAlias;
        // The number of NFT tokens.
        uint32 ownedLength;
        // The token balance in wei.
        uint96 balance;
    }

    /// @dev A uint32 map in storage.
    struct Uint32Map {
        uint256 spacer;
    }

    /// @dev A bitmap in storage.
    struct Bitmap {
        uint256 spacer;
    }

    /// @dev A struct to wrap a uint256 in storage.
    struct Uint256Ref {
        uint256 value;
    }

    /// @dev A mapping of an address pair to a Uint256Ref.
    struct AddressPairToUint256RefMap {
        uint256 spacer;
    }

    /// @dev Struct containing the base token contract storage.
    struct DN404Storage {
        // Current number of address aliases assigned.
        uint32 numAliases;
        // Next token ID to assign for an NFT mint.
        uint32 nextTokenId;
        // Total number of IDs in the burned pool.
        uint32 burnedPoolSize;
        // Total supply of minted NFTs.
        uint32 totalNFTSupply;
        // Total supply of tokens.
        uint96 totalSupply;
        // Address of the NFT mirror contract.
        address mirrorERC721;
        // Mapping of a user alias number to their address.
        mapping(uint32 => address) aliasToAddress;
        // Mapping of user operator approvals for NFTs.
        AddressPairToUint256RefMap operatorApprovals;
        // Mapping of NFT token approvals to approved operators.
        mapping(uint256 => address) nftApprovals;
        // Bitmap of whether an non-zero NFT approval may exist.
        Bitmap mayHaveNFTApproval;
        // Mapping of user allowances for token spenders.
        AddressPairToUint256RefMap allowance;
        // Mapping of NFT IDs owned by an address.
        mapping(address => Uint32Map) owned;
        // The pool of burned NFT IDs.
        Uint32Map burnedPool;
        // Even indices: owner aliases. Odd indices: owned indices.
        Uint32Map oo;
        // Mapping of user account AddressData.
        mapping(address => AddressData) addressData;
    }

    /// @dev Returns a storage pointer for DN404Storage.
    function _getDN404Storage() internal pure virtual returns (DN404Storage storage $) {
        /// @solidity memory-safe-assembly
        assembly {
        // `uint72(bytes9(keccak256("DN404_STORAGE")))`.
            $.slot := 0xa20d6e21d0e5255308 // Truncate to 9 bytes to reduce bytecode size.
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                         INITIALIZER                        */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Initializes the DN404 contract with an
    /// `initialTokenSupply`, `initialTokenOwner` and `mirror` NFT contract address.
    function _initializeDN404(
        uint256 initialTokenSupply,
        address initialSupplyOwner,
        address mirror
    ) internal virtual {
        DN404Storage storage $ = _getDN404Storage();

        if ($.nextTokenId != 0) revert DNAlreadyInitialized();

        if (mirror == address(0)) revert MirrorAddressIsZero();

        /// @solidity memory-safe-assembly
        assembly {
        // Make the call to link the mirror contract.
            mstore(0x00, 0x0f4599e5) // `linkMirrorContract(address)`.
            mstore(0x20, caller())
            if iszero(and(eq(mload(0x00), 1), call(gas(), mirror, 0, 0x1c, 0x24, 0x00, 0x20))) {
                mstore(0x00, 0xd125259c) // `LinkMirrorContractFailed()`.
                revert(0x1c, 0x04)
            }
        }

        $.nextTokenId = 1;
        $.mirrorERC721 = mirror;

        if (_unit() == 0) revert UnitIsZero();

        if (initialTokenSupply != 0) {
            if (initialSupplyOwner == address(0)) revert TransferToZeroAddress();
            if (_totalSupplyOverflows(initialTokenSupply)) revert TotalSupplyOverflow();

            $.totalSupply = uint96(initialTokenSupply);
            AddressData storage initialOwnerAddressData = _addressData(initialSupplyOwner);
            initialOwnerAddressData.balance = uint96(initialTokenSupply);

            /// @solidity memory-safe-assembly
            assembly {
            // Emit the {Transfer} event.
                mstore(0x00, initialTokenSupply)
                log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, 0, shr(96, shl(96, initialSupplyOwner)))
            }

            _setSkipNFT(initialSupplyOwner, true);
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*               BASE UNIT FUNCTION TO OVERRIDE               */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Amount of token balance that is equal to one NFT.
    function _unit() internal view virtual returns (uint256) {
        return 10 ** 18;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*               METADATA FUNCTIONS TO OVERRIDE               */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the name of the token.
    function name() public view virtual returns (string memory);

    /// @dev Returns the symbol of the token.
    function symbol() public view virtual returns (string memory);

    /// @dev Returns the Uniform Resource Identifier (URI) for token `id`.
    function tokenURI(uint256 id) public view virtual returns (string memory);

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                      ERC20 OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the decimals places of the token. Always 18.
    function decimals() public pure returns (uint8) {
        return 18;
    }

    /// @dev Returns the amount of tokens in existence.
    function totalSupply() public view virtual returns (uint256) {
        return uint256(_getDN404Storage().totalSupply);
    }

    /// @dev Returns the amount of tokens owned by `owner`.
    function balanceOf(address owner) public view virtual returns (uint256) {
        return _getDN404Storage().addressData[owner].balance;
    }

    /// @dev Returns the amount of tokens that `spender` can spend on behalf of `owner`.
    function allowance(address owner, address spender) public view returns (uint256) {
        if (_givePermit2DefaultInfiniteAllowance() && spender == _PERMIT2) {
            uint8 flags = _getDN404Storage().addressData[owner].flags;
            if (flags & _ADDRESS_DATA_OVERRIDE_PERMIT2_FLAG == 0) return type(uint256).max;
        }
        return _ref(_getDN404Storage().allowance, owner, spender).value;
    }

    /// @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
    ///
    /// Emits a {Approval} event.
    function approve(address spender, uint256 amount) public virtual returns (bool) {
        _approve(msg.sender, spender, amount);
        return true;
    }

    /// @dev Transfer `amount` tokens from the caller to `to`.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Requirements:
    /// - `from` must at least have `amount`.
    ///
    /// Emits a {Transfer} event.
    function transfer(address to, uint256 amount) public virtual returns (bool) {
        _transfer(msg.sender, to, amount);
        return true;
    }

    /// @dev Transfers `amount` tokens from `from` to `to`.
    ///
    /// Note: Does not update the allowance if it is the maximum uint256 value.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Requirements:
    /// - `from` must at least have `amount`.
    /// - The caller must have at least `amount` of allowance to transfer the tokens of `from`.
    ///
    /// Emits a {Transfer} event.
    function transferFrom(address from, address to, uint256 amount) public virtual returns (bool) {
        Uint256Ref storage a = _ref(_getDN404Storage().allowance, from, msg.sender);

        uint256 allowed = _givePermit2DefaultInfiniteAllowance() && msg.sender == _PERMIT2
        && (_getDN404Storage().addressData[from].flags & _ADDRESS_DATA_OVERRIDE_PERMIT2_FLAG) == 0
            ? type(uint256).max
            : a.value;

        if (allowed != type(uint256).max) {
            if (amount > allowed) revert InsufficientAllowance();
            unchecked {
                a.value = allowed - amount;
            }
        }
        _transfer(from, to, amount);
        return true;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                          PERMIT2                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Whether Permit2 has infinite allowances by default for all owners.
    /// For signature-based allowance granting for single transaction ERC20 `transferFrom`.
    /// To enable, override this function to return true.
    function _givePermit2DefaultInfiniteAllowance() internal view virtual returns (bool) {
        return false;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                  INTERNAL MINT FUNCTIONS                   */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Mints `amount` tokens to `to`, increasing the total supply.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Emits a {Transfer} event.
    function _mint(address to, uint256 amount) internal virtual {
        if (to == address(0)) revert TransferToZeroAddress();

        DN404Storage storage $ = _getDN404Storage();

        AddressData storage toAddressData = _addressData(to);

        unchecked {
            uint256 maxNFTId;
            {
                uint256 totalSupply_ = uint256($.totalSupply) + amount;
                $.totalSupply = uint96(totalSupply_);
                uint256 overflows = _toUint(_totalSupplyOverflows(totalSupply_));
                if (overflows | _toUint(totalSupply_ < amount) != 0) revert TotalSupplyOverflow();
                maxNFTId = totalSupply_ / _unit();
            }
            uint256 toEnd;
            {
                uint256 toBalance = uint256(toAddressData.balance) + amount;
                toAddressData.balance = uint96(toBalance);
                toEnd = toBalance / _unit();
            }
            if (toAddressData.flags & _ADDRESS_DATA_SKIP_NFT_FLAG == 0) {
                Uint32Map storage toOwned = $.owned[to];
                Uint32Map storage oo = $.oo;
                uint256 toIndex = toAddressData.ownedLength;
                _PackedLogs memory packedLogs = _packedLogsMalloc(_zeroFloorSub(toEnd, toIndex));

                if (packedLogs.logs.length != 0) {
                    _packedLogsSet(packedLogs, to, 0);
                    uint256 burnedPoolSize = $.burnedPoolSize;
                    uint256 nextTokenId = $.nextTokenId;
                    uint32 toAlias = _registerAndResolveAlias(toAddressData, to);
                    $.totalNFTSupply += uint32(packedLogs.logs.length);
                    toAddressData.ownedLength = uint32(toEnd);
                    // Mint loop.
                    do {
                        uint256 id;
                        if (burnedPoolSize != 0) {
                            id = _get($.burnedPool, --burnedPoolSize);
                        } else {
                            id = nextTokenId;
                            while (_get(oo, _ownershipIndex(id)) != 0) {
                                id = _wrapNFTId(id + 1, maxNFTId);
                            }
                            nextTokenId = _wrapNFTId(id + 1, maxNFTId);
                        }
                        _set(toOwned, toIndex, uint32(id));
                        _setOwnerAliasAndOwnedIndex(oo, id, toAlias, uint32(toIndex++));
                        _packedLogsAppend(packedLogs, id);
                    } while (toIndex != toEnd);

                    // Leave some spacing between minted batches for better open addressing.
                    $.nextTokenId = uint32(_wrapNFTId(nextTokenId + 7, maxNFTId));
                    $.burnedPoolSize = uint32(burnedPoolSize);
                    _packedLogsSend(packedLogs, $.mirrorERC721);
                }
            }
        }
        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Transfer} event.
            mstore(0x00, amount)
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, 0, shr(96, shl(96, to)))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                  INTERNAL BURN FUNCTIONS                   */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Burns `amount` tokens from `from`, reducing the total supply.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Emits a {Transfer} event.
    function _burn(address from, uint256 amount) internal virtual {
        DN404Storage storage $ = _getDN404Storage();

        AddressData storage fromAddressData = _addressData(from);

        uint256 fromBalance = fromAddressData.balance;
        if (amount > fromBalance) revert InsufficientBalance();

        unchecked {
            fromAddressData.balance = uint96(fromBalance -= amount);
            uint256 totalSupply_ = uint256($.totalSupply) - amount;
            $.totalSupply = uint96(totalSupply_);

            Uint32Map storage fromOwned = $.owned[from];
            uint256 fromIndex = fromAddressData.ownedLength;
            uint256 numNFTBurns = _zeroFloorSub(fromIndex, fromBalance / _unit());

            if (numNFTBurns != 0) {
                _PackedLogs memory packedLogs = _packedLogsMalloc(numNFTBurns);
                _packedLogsSet(packedLogs, from, 1);
                uint256 totalNFTSupply = uint256($.totalNFTSupply) - numNFTBurns;
                $.totalNFTSupply = uint32(totalNFTSupply);
                bool addToBurnedPool = _addToBurnedPool(totalNFTSupply, totalSupply_);

                Uint32Map storage oo = $.oo;
                uint256 fromEnd = fromIndex - numNFTBurns;
                fromAddressData.ownedLength = uint32(fromEnd);
                uint256 burnedPoolSize = $.burnedPoolSize;
                // Burn loop.
                do {
                    uint256 id = _get(fromOwned, --fromIndex);
                    _setOwnerAliasAndOwnedIndex(oo, id, 0, 0);
                    _packedLogsAppend(packedLogs, id);
                    if (addToBurnedPool) {
                        _set($.burnedPool, burnedPoolSize++, uint32(id));
                    }
                    if (_get($.mayHaveNFTApproval, id)) {
                        _set($.mayHaveNFTApproval, id, false);
                        delete $.nftApprovals[id];
                    }
                } while (fromIndex != fromEnd);

                $.burnedPoolSize = uint32(burnedPoolSize);
                _packedLogsSend(packedLogs, $.mirrorERC721);
            }
        }
        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Transfer} event.
            mstore(0x00, amount)
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, shl(96, from)), 0)
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                INTERNAL TRANSFER FUNCTIONS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Moves `amount` of tokens from `from` to `to`.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Emits a {Transfer} event.
    function _transfer(address from, address to, uint256 amount) internal virtual {
        if (to == address(0)) revert TransferToZeroAddress();

        DN404Storage storage $ = _getDN404Storage();

        AddressData storage fromAddressData = _addressData(from);
        AddressData storage toAddressData = _addressData(to);

        _TransferTemps memory t;
        t.fromOwnedLength = fromAddressData.ownedLength;
        t.toOwnedLength = toAddressData.ownedLength;
        t.totalSupply = $.totalSupply;

        if (amount > (t.fromBalance = fromAddressData.balance)) revert InsufficientBalance();

        unchecked {
            fromAddressData.balance = uint96(t.fromBalance -= amount);
            toAddressData.balance = uint96(t.toBalance = uint256(toAddressData.balance) + amount);

            t.numNFTBurns = _zeroFloorSub(t.fromOwnedLength, t.fromBalance / _unit());

            if (toAddressData.flags & _ADDRESS_DATA_SKIP_NFT_FLAG == 0) {
                if (from == to) t.toOwnedLength = t.fromOwnedLength - t.numNFTBurns;
                t.numNFTMints = _zeroFloorSub(t.toBalance / _unit(), t.toOwnedLength);
            }

            t.totalNFTSupply = uint256($.totalNFTSupply) + t.numNFTMints - t.numNFTBurns;
            $.totalNFTSupply = uint32(t.totalNFTSupply);

            _PackedLogs memory packedLogs = _packedLogsMalloc(t.numNFTBurns + t.numNFTMints);
            Uint32Map storage oo = $.oo;

            uint256 burnedPoolSize = $.burnedPoolSize;
            if (t.numNFTBurns != 0) {
                _packedLogsSet(packedLogs, from, 1);
                bool addToBurnedPool = _addToBurnedPool(t.totalNFTSupply, t.totalSupply);
                Uint32Map storage fromOwned = $.owned[from];
                uint256 fromIndex = t.fromOwnedLength;
                uint256 fromEnd = fromIndex - t.numNFTBurns;
                fromAddressData.ownedLength = uint32(fromEnd);
                // Burn loop.
                do {
                    uint256 id = _get(fromOwned, --fromIndex);
                    _setOwnerAliasAndOwnedIndex(oo, id, 0, 0);
                    _packedLogsAppend(packedLogs, id);
                    if (addToBurnedPool) {
                        _set($.burnedPool, burnedPoolSize++, uint32(id));
                    }
                    if (_get($.mayHaveNFTApproval, id)) {
                        _set($.mayHaveNFTApproval, id, false);
                        delete $.nftApprovals[id];
                    }
                } while (fromIndex != fromEnd);
            }

            if (t.numNFTMints != 0) {
                _packedLogsSet(packedLogs, to, 0);
                uint256 nextTokenId = $.nextTokenId;
                Uint32Map storage toOwned = $.owned[to];
                uint256 toIndex = t.toOwnedLength;
                uint256 toEnd = toIndex + t.numNFTMints;
                uint32 toAlias = _registerAndResolveAlias(toAddressData, to);
                uint256 maxNFTId = t.totalSupply / _unit();
                toAddressData.ownedLength = uint32(toEnd);
                // Mint loop.
                do {
                    uint256 id;
                    if (burnedPoolSize != 0) {
                        id = _get($.burnedPool, --burnedPoolSize);
                    } else {
                        id = nextTokenId;
                        while (_get(oo, _ownershipIndex(id)) != 0) {
                            id = _wrapNFTId(id + 1, maxNFTId);
                        }
                        nextTokenId = _wrapNFTId(id + 1, maxNFTId);
                    }
                    _set(toOwned, toIndex, uint32(id));
                    _setOwnerAliasAndOwnedIndex(oo, id, toAlias, uint32(toIndex++));
                    _packedLogsAppend(packedLogs, id);
                } while (toIndex != toEnd);

                // Leave some spacing between minted batches for better open addressing.
                $.nextTokenId = uint32(_wrapNFTId(nextTokenId + 7, maxNFTId));
            }

            if (packedLogs.logs.length != 0) {
                $.burnedPoolSize = uint32(burnedPoolSize);
                _packedLogsSend(packedLogs, $.mirrorERC721);
            }
        }
        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Transfer} event.
            mstore(0x00, amount)
        // forgefmt: disable-next-item
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, shl(96, from)), shr(96, shl(96, to)))
        }
    }

    /// @dev Returns if burns should be added to the burn pool.
    function _addToBurnedPool(uint256 totalNFTSupplyAfterBurn, uint256 totalSupplyAfterBurn)
    internal
    view
    virtual
    returns (bool)
    {
        // Add to burned pool if the load factor > 50%, and collection is not small.
        uint256 thres = (totalSupplyAfterBurn / _unit()) >> 1;
        return _toUint(totalNFTSupplyAfterBurn > thres) & _toUint(thres > 128) != 0;
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Call must originate from the mirror contract.
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    ///   `msgSender` must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function _transferFromNFT(address from, address to, uint256 id, address msgSender)
    internal
    virtual
    {
        DN404Storage storage $ = _getDN404Storage();

        if (to == address(0)) revert TransferToZeroAddress();

        Uint32Map storage oo = $.oo;

        if (from != $.aliasToAddress[_get(oo, _ownershipIndex(id))]) {
            revert TransferFromIncorrectOwner();
        }

        if (msgSender != from) {
            if (_ref($.operatorApprovals, from, msgSender).value == 0) {
                if (msgSender != $.nftApprovals[id]) {
                    revert TransferCallerNotOwnerNorApproved();
                }
            }
        }

        AddressData storage fromAddressData = _addressData(from);
        AddressData storage toAddressData = _addressData(to);

        uint256 unit = _unit();

        unchecked {
            {
                uint256 fromBalance = fromAddressData.balance;
                if (unit > fromBalance) revert InsufficientBalance();
                fromAddressData.balance = uint96(fromBalance - unit);
                toAddressData.balance += uint96(unit);
            }
            mapping(address => Uint32Map) storage owned = $.owned;
            Uint32Map storage fromOwned = owned[from];

            if (_get($.mayHaveNFTApproval, id)) {
                _set($.mayHaveNFTApproval, id, false);
                delete $.nftApprovals[id];
            }

            {
                uint32 updatedId = _get(fromOwned, --fromAddressData.ownedLength);
                uint32 i = _get(oo, _ownedIndex(id));
                _set(fromOwned, i, updatedId);
                _set(oo, _ownedIndex(updatedId), i);
            }
            uint32 n = toAddressData.ownedLength++;
            _set(owned[to], n, uint32(id));
            _setOwnerAliasAndOwnedIndex(oo, id, _registerAndResolveAlias(toAddressData, to), n);
        }

        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Transfer} event.
            mstore(0x00, unit)
        // forgefmt: disable-next-item
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, shl(96, from)), shr(96, shl(96, to)))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                 INTERNAL APPROVE FUNCTIONS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Sets `amount` as the allowance of `spender` over the tokens of `owner`.
    ///
    /// Emits a {Approval} event.
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        if (_givePermit2DefaultInfiniteAllowance() && spender == _PERMIT2) {
            _getDN404Storage().addressData[owner].flags |= _ADDRESS_DATA_OVERRIDE_PERMIT2_FLAG;
        }
        _ref(_getDN404Storage().allowance, owner, spender).value = amount;
        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Approval} event.
            mstore(0x00, amount)
        // forgefmt: disable-next-item
            log3(0x00, 0x20, _APPROVAL_EVENT_SIGNATURE, shr(96, shl(96, owner)), shr(96, shl(96, spender)))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                 DATA HITCHHIKING FUNCTIONS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the auxiliary data for `owner`.
    /// Minting, transferring, burning the tokens of `owner` will not change the auxiliary data.
    /// Auxiliary data can be set for any address, even if it does not have any tokens.
    function _getAux(address owner) internal view virtual returns (uint88) {
        return _getDN404Storage().addressData[owner].aux;
    }

    /// @dev Set the auxiliary data for `owner` to `value`.
    /// Minting, transferring, burning the tokens of `owner` will not change the auxiliary data.
    /// Auxiliary data can be set for any address, even if it does not have any tokens.
    function _setAux(address owner, uint88 value) internal virtual {
        _getDN404Storage().addressData[owner].aux = value;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     SKIP NFT FUNCTIONS                     */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns true if minting and transferring ERC20s to `owner` will skip minting NFTs.
    /// Returns false otherwise.
    function getSkipNFT(address owner) public view virtual returns (bool) {
        AddressData storage d = _getDN404Storage().addressData[owner];
        if (d.flags & _ADDRESS_DATA_INITIALIZED_FLAG == 0) return _hasCode(owner);
        return d.flags & _ADDRESS_DATA_SKIP_NFT_FLAG != 0;
    }

    /// @dev Sets the caller's skipNFT flag to `skipNFT`. Returns true.
    ///
    /// Emits a {SkipNFTSet} event.
    function setSkipNFT(bool skipNFT) public virtual returns (bool) {
        _setSkipNFT(msg.sender, skipNFT);
        return true;
    }

    /// @dev Internal function to set account `owner` skipNFT flag to `state`
    ///
    /// Initializes account `owner` AddressData if it is not currently initialized.
    ///
    /// Emits a {SkipNFTSet} event.
    function _setSkipNFT(address owner, bool state) internal virtual {
        AddressData storage d = _addressData(owner);
        if ((d.flags & _ADDRESS_DATA_SKIP_NFT_FLAG != 0) != state) {
            d.flags ^= _ADDRESS_DATA_SKIP_NFT_FLAG;
        }
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, iszero(iszero(state)))
            log2(0x00, 0x20, _SKIP_NFT_SET_EVENT_SIGNATURE, shr(96, shl(96, owner)))
        }
    }

    /// @dev Returns a storage data pointer for account `owner` AddressData
    ///
    /// Initializes account `owner` AddressData if it is not currently initialized.
    function _addressData(address owner) internal virtual returns (AddressData storage d) {
        d = _getDN404Storage().addressData[owner];
        unchecked {
            if (d.flags & _ADDRESS_DATA_INITIALIZED_FLAG == 0) {
                uint256 skipNFT = (_toUint(_hasCode(owner)) * _ADDRESS_DATA_SKIP_NFT_FLAG);
                d.flags = uint8(skipNFT | _ADDRESS_DATA_INITIALIZED_FLAG);
            }
        }
    }

    /// @dev Returns the `addressAlias` of account `to`.
    ///
    /// Assigns and registers the next alias if `to` alias was not previously registered.
    function _registerAndResolveAlias(AddressData storage toAddressData, address to)
    internal
    virtual
    returns (uint32 addressAlias)
    {
        DN404Storage storage $ = _getDN404Storage();
        addressAlias = toAddressData.addressAlias;
        if (addressAlias == 0) {
            unchecked {
                addressAlias = ++$.numAliases;
            }
            toAddressData.addressAlias = addressAlias;
            $.aliasToAddress[addressAlias] = to;
            if (addressAlias == 0) revert(); // Overflow.
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     MIRROR OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the address of the mirror NFT contract.
    function mirrorERC721() public view virtual returns (address) {
        return _getDN404Storage().mirrorERC721;
    }

    /// @dev Returns the total NFT supply.
    function _totalNFTSupply() internal view virtual returns (uint256) {
        return _getDN404Storage().totalNFTSupply;
    }

    /// @dev Returns `owner` NFT balance.
    function _balanceOfNFT(address owner) internal view virtual returns (uint256) {
        return _getDN404Storage().addressData[owner].ownedLength;
    }

    /// @dev Returns the owner of token `id`.
    /// Returns the zero address instead of reverting if the token does not exist.
    function _ownerAt(uint256 id) internal view virtual returns (address) {
        DN404Storage storage $ = _getDN404Storage();
        return $.aliasToAddress[_get($.oo, _ownershipIndex(id))];
    }

    /// @dev Returns the owner of token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function _ownerOf(uint256 id) internal view virtual returns (address) {
        if (!_exists(id)) revert TokenDoesNotExist();
        return _ownerAt(id);
    }

    /// @dev Returns if token `id` exists.
    function _exists(uint256 id) internal view virtual returns (bool) {
        return _ownerAt(id) != address(0);
    }

    /// @dev Returns the account approved to manage token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function _getApproved(uint256 id) internal view virtual returns (address) {
        if (!_exists(id)) revert TokenDoesNotExist();
        return _getDN404Storage().nftApprovals[id];
    }

    /// @dev Sets `spender` as the approved account to manage token `id`, using `msgSender`.
    ///
    /// Requirements:
    /// - `msgSender` must be the owner or an approved operator for the token owner.
    function _approveNFT(address spender, uint256 id, address msgSender)
    internal
    virtual
    returns (address owner)
    {
        DN404Storage storage $ = _getDN404Storage();

        owner = $.aliasToAddress[_get($.oo, _ownershipIndex(id))];

        if (msgSender != owner) {
            if (_ref($.operatorApprovals, owner, msgSender).value == 0) {
                revert ApprovalCallerNotOwnerNorApproved();
            }
        }

        $.nftApprovals[id] = spender;
        _set($.mayHaveNFTApproval, id, spender != address(0));
    }

    /// @dev Approve or remove the `operator` as an operator for `msgSender`,
    /// without authorization checks.
    function _setApprovalForAll(address operator, bool approved, address msgSender)
    internal
    virtual
    {
        _ref(_getDN404Storage().operatorApprovals, msgSender, operator).value = _toUint(approved);
    }

    /// @dev Fallback modifier to dispatch calls from the mirror NFT contract
    /// to internal functions in this contract.
    modifier dn404Fallback() virtual {
        DN404Storage storage $ = _getDN404Storage();

        uint256 fnSelector = _calldataload(0x00) >> 224;

        // `transferFromNFT(address,address,uint256,address)`.
        if (fnSelector == 0xe5eb36c8) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x84) revert();

            address from = address(uint160(_calldataload(0x04)));
            address to = address(uint160(_calldataload(0x24)));
            uint256 id = _calldataload(0x44);
            address msgSender = address(uint160(_calldataload(0x64)));

            _transferFromNFT(from, to, id, msgSender);
            _return(1);
        }
        // `setApprovalForAll(address,bool,address)`.
        if (fnSelector == 0x813500fc) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x64) revert();

            address spender = address(uint160(_calldataload(0x04)));
            bool status = _calldataload(0x24) != 0;
            address msgSender = address(uint160(_calldataload(0x44)));

            _setApprovalForAll(spender, status, msgSender);
            _return(1);
        }
        // `isApprovedForAll(address,address)`.
        if (fnSelector == 0xe985e9c5) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x44) revert();

            address owner = address(uint160(_calldataload(0x04)));
            address operator = address(uint160(_calldataload(0x24)));

            _return(_ref($.operatorApprovals, owner, operator).value);
        }
        // `ownerOf(uint256)`.
        if (fnSelector == 0x6352211e) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            uint256 id = _calldataload(0x04);

            _return(uint160(_ownerOf(id)));
        }
        // `ownerAt(uint256)`.
        if (fnSelector == 0x24359879) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            uint256 id = _calldataload(0x04);

            _return(uint160(_ownerAt(id)));
        }
        // `approveNFT(address,uint256,address)`.
        if (fnSelector == 0xd10b6e0c) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x64) revert();

            address spender = address(uint160(_calldataload(0x04)));
            uint256 id = _calldataload(0x24);
            address msgSender = address(uint160(_calldataload(0x44)));

            _return(uint160(_approveNFT(spender, id, msgSender)));
        }
        // `getApproved(uint256)`.
        if (fnSelector == 0x081812fc) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            uint256 id = _calldataload(0x04);

            _return(uint160(_getApproved(id)));
        }
        // `balanceOfNFT(address)`.
        if (fnSelector == 0xf5b100ea) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            address owner = address(uint160(_calldataload(0x04)));

            _return(_balanceOfNFT(owner));
        }
        // `totalNFTSupply()`.
        if (fnSelector == 0xe2c79281) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x04) revert();

            _return(_totalNFTSupply());
        }
        // `implementsDN404()`.
        if (fnSelector == 0xb7a94eb8) {
            _return(1);
        }
        _;
    }

    /// @dev Fallback function for calls from mirror NFT contract.
    fallback() external payable virtual dn404Fallback {}

    receive() external payable virtual {}

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                 INTERNAL / PRIVATE HELPERS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns `(i - 1) << 1`.
    function _ownershipIndex(uint256 i) internal pure returns (uint256) {
        unchecked {
            return (i - 1) << 1; // Minus 1 as token IDs start from 1.
        }
    }

    /// @dev Returns `((i - 1) << 1) + 1`.
    function _ownedIndex(uint256 i) internal pure returns (uint256) {
        unchecked {
            return ((i - 1) << 1) + 1; // Minus 1 as token IDs start from 1.
        }
    }

    /// @dev Returns the uint32 value at `index` in `map`.
    function _get(Uint32Map storage map, uint256 index) internal view returns (uint32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            let s := add(shl(96, map.slot), shr(3, index)) // Storage slot.
            result := and(0xffffffff, shr(shl(5, and(index, 7)), sload(s)))
        }
    }

    /// @dev Updates the uint32 value at `index` in `map`.
    function _set(Uint32Map storage map, uint256 index, uint32 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            let s := add(shl(96, map.slot), shr(3, index)) // Storage slot.
            let o := shl(5, and(index, 7)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Sets the owner alias and the owned index together.
    function _setOwnerAliasAndOwnedIndex(
        Uint32Map storage map,
        uint256 id,
        uint32 ownership,
        uint32 ownedIndex
    ) internal {
        /// @solidity memory-safe-assembly
        assembly {
            let i := sub(id, 1) // Index of the uint64 combined value.
            let s := add(shl(96, map.slot), shr(2, i)) // Storage slot.
            let o := shl(6, and(i, 3)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffffffffff // Value mask.
            let combined := or(shl(32, ownedIndex), and(0xffffffff, ownership))
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), combined)))))
        }
    }

    /// @dev Returns the boolean value of the bit at `index` in `bitmap`.
    function _get(Bitmap storage bitmap, uint256 index) internal view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            let s := add(shl(96, bitmap.slot), shr(8, index)) // Storage slot.
            result := and(1, shr(and(0xff, index), sload(s)))
        }
    }

    /// @dev Updates the bit at `index` in `bitmap` to `value`.
    function _set(Bitmap storage bitmap, uint256 index, bool value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            let s := add(shl(96, bitmap.slot), shr(8, index)) // Storage slot.
            let o := and(0xff, index) // Storage slot offset (bits).
            sstore(s, or(and(sload(s), not(shl(o, 1))), shl(o, iszero(iszero(value)))))
        }
    }

    /// @dev Returns a storage reference to the value at (`a0`, `a1`) in `map`.
    function _ref(AddressPairToUint256RefMap storage map, address a0, address a1)
    internal
    pure
    returns (Uint256Ref storage ref)
    {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x28, a1)
            mstore(0x14, a0)
            mstore(0x00, map.slot)
            ref.slot := keccak256(0x00, 0x48)
        // Clear the part of the free memory pointer that was overwritten.
            mstore(0x28, 0x00)
        }
    }

    /// @dev Wraps the NFT ID.
    function _wrapNFTId(uint256 id, uint256 maxNFTId) internal pure returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := or(mul(iszero(gt(id, maxNFTId)), id), gt(id, maxNFTId))
        }
    }

    /// @dev Returns whether `amount` is a valid `totalSupply`.
    function _totalSupplyOverflows(uint256 amount) internal view returns (bool) {
        unchecked {
            return _toUint(amount > type(uint96).max)
            | _toUint(amount / _unit() > type(uint32).max - 1) != 0;
        }
    }

    /// @dev Returns `max(0, x - y)`.
    function _zeroFloorSub(uint256 x, uint256 y) internal pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            z := mul(gt(x, y), sub(x, y))
        }
    }

    /// @dev Returns `b ? 1 : 0`.
    function _toUint(bool b) internal pure returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := iszero(iszero(b))
        }
    }

    /// @dev Struct containing packed log data for {Transfer} events to be
    /// emitted by the mirror NFT contract.
    struct _PackedLogs {
        uint256 offset;
        uint256 addressAndBit;
        uint256[] logs;
    }

    /// @dev Initiates memory allocation for packed logs with `n` log items.
    function _packedLogsMalloc(uint256 n) private pure returns (_PackedLogs memory p) {
        /// @solidity memory-safe-assembly
        assembly {
        // Note that `p` implicitly allocates and advances the free memory pointer by
        // 3 words, which we can safely mutate in `_packedLogsSend`.
            let logs := mload(0x40)
            mstore(logs, n) // Store the length.
            let offset := add(0x20, logs) // Skip the word for `p.logs.length`.
            mstore(0x40, add(offset, shl(5, n))) // Allocate memory.
            mstore(add(0x40, p), logs) // Set `p.logs`.
            mstore(p, offset) // Set `p.offset`.
        }
    }

    /// @dev Set the current address and the burn bit.
    function _packedLogsSet(_PackedLogs memory p, address a, uint256 burnBit) private pure {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(add(p, 0x20), or(shl(96, a), burnBit)) // Set `p.addressAndBit`.
        }
    }

    /// @dev Adds a packed log item to `p` with token `id`.
    function _packedLogsAppend(_PackedLogs memory p, uint256 id) private pure {
        /// @solidity memory-safe-assembly
        assembly {
            let offset := mload(p)
            mstore(offset, or(mload(add(p, 0x20)), shl(8, id))) // `p.addressAndBit | (id << 8)`.
            mstore(p, add(offset, 0x20))
        }
    }

    /// @dev Calls the `mirror` NFT contract to emit {Transfer} events for packed logs `p`.
    function _packedLogsSend(_PackedLogs memory p, address mirror) private {
        /// @solidity memory-safe-assembly
        assembly {
            let logs := mload(add(p, 0x40))
            let o := sub(logs, 0x40) // Start of calldata to send.
            mstore(o, 0x263c69d6) // `logTransfer(uint256[])`.
            mstore(add(o, 0x20), 0x20) // Offset of `logs` in the calldata to send.
            let n := add(0x44, shl(5, mload(logs))) // Length of calldata to send.
            if iszero(and(eq(mload(o), 1), call(gas(), mirror, 0, add(o, 0x1c), n, o, 0x20))) {
                revert(o, 0x00)
            }
        }
    }

    /// @dev Struct of temporary variables for transfers.
    struct _TransferTemps {
        uint256 numNFTBurns;
        uint256 numNFTMints;
        uint256 fromBalance;
        uint256 toBalance;
        uint256 fromOwnedLength;
        uint256 toOwnedLength;
        uint256 totalSupply;
        uint256 totalNFTSupply;
    }

    /// @dev Returns if `a` has bytecode of non-zero length.
    function _hasCode(address a) private view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := extcodesize(a) // Can handle dirty upper bits.
        }
    }

    /// @dev Returns the calldata value at `offset`.
    function _calldataload(uint256 offset) private pure returns (uint256 value) {
        /// @solidity memory-safe-assembly
        assembly {
            value := calldataload(offset)
        }
    }

    /// @dev Executes a return opcode to return `x` and end the current call frame.
    function _return(uint256 x) private pure {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, x)
            return(0x00, 0x20)
        }
    }
}

interface IERC20 {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address to, uint256 value) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 value) external returns (bool);
    function transferFrom(address from, address to, uint256 value) external returns (bool);
}


/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @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);
    }
}

interface IUniswapV2Factory {
    event PairCreated(
        address indexed token0,
        address indexed token1,
        address pair,
        uint256
    );

    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(uint256) external view returns (address pair);

    function allPairsLength() external view returns (uint256);

    function createPair(address tokenA, address tokenB)
    external
    returns (address pair);

    function setFeeTo(address) external;

    function setFeeToSetter(address) external;
}

contract YBOYZ is ERC_YB, Ownable {
    ERC_YB_NFT private _mirror;

    using Strings for uint256;

    error TransferFailed();

    string public baseTokenURI = "https://jvwgtygk3tt6jgfavflntvhahksrk6pqzznp4ehau5yebjg3azja.arweave.net/TWxp4Mrc5-SYoKlW2dTgOqUVefDOWv4Q4KdwQKTbBlI/";

    IUniswapV2Router02 public immutable _uniswapV2Router;

    address public immutable uniswapV2Pair;
    address private deployerWallet;
    address private marketingWallet;
    address private constant deadAddress = address(0xdead);

    bool private swapping;

    uint256 public initialNftSupply = 10000;
    uint256 public initialTotalSupply = initialNftSupply * 1e18;
    // swap fee for ETH at 0.1% supply
    uint256 public swapTokensAtAmount = (initialTotalSupply * 5)/1000;

    // a single wallet can hold up to 2.5% of the total supply
    uint256 public maxWallet = (initialTotalSupply * 25)/1000;
    uint256 public maxTransactionAmount = maxWallet;

    bool public tradingOpen = false;
    bool public swapEnabled = false;

    uint256 public buyFee = 0;
    uint256 public sellFee = 0;

    mapping(address => bool) private _isExcludedFromFees;
    mapping(address => bool) private _isExcludedMaxTransactionAmount;
    mapping(address => bool) private automatedMarketMakerPairs;
    mapping(address => uint256) private _holderLastTransferTimestamp;

    event ExcludeFromFees(address indexed account, bool isExcluded);
    event SetAutomatedMarketMakerPair(address indexed pair, bool indexed value);

    uint8 private constant _decimals = 18;
//    uint256 private constant _totalTokens = 10_000;
    uint256 private constant _tokensPerNFT = 1;
    string private constant _name = "YBOYZ";
    string private constant _symbol = "YardBoyz";

    constructor() {
        _initializeOwner(msg.sender);

        _mirror = new ERC_YB_NFT(owner());
        _initializeDN404(initialTotalSupply, msg.sender, address(_mirror));

        _setSkipNFT(msg.sender, true);
        _setSkipNFT(address (this), true);
//        balanceOf(msg.sender) = initialTotalSupply;
//        _mintERC20(msg.sender, initialTotalSupply, false);

        // sepolia net 0x86dcd3293C53Cf8EFd7303B57beb2a3F671dDE98
        _uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        marketingWallet = payable(msg.sender);
        deployerWallet = payable(msg.sender);

        // exclude router, contract, and dead address from maxTransactionAmount
        excludeFromMaxTransaction(address(_uniswapV2Router), true);
        excludeFromMaxTransaction(address(this), true);
        excludeFromMaxTransaction(address(0xdead), true);

        // exclude deployer and marketing wallet from maxTransactionAmount
        excludeFromMaxTransaction(address(msg.sender), true);
        excludeFromMaxTransaction(msg.sender, true);
        excludeFromMaxTransaction(marketingWallet, true);

        // exclude contract and dead address from fees
        excludeFromFees(address(this), true);
        excludeFromFees(address(0xdead), true);

        // exclude deployer and marketingWallet from fees
        excludeFromFees(address(msg.sender), true);
        excludeFromFees(msg.sender, true);
        excludeFromFees(marketingWallet, true);

        uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(
            address(this),
            _uniswapV2Router.WETH()
        );
        _setSkipNFT(uniswapV2Pair, true);
    }

    function name() public view override returns (string memory) {
        return _name;
    }

    function symbol() public view override returns (string memory) {
        return _symbol;
    }

    function setTokenURI(string memory _tokenURI) public onlyOwner {
        baseTokenURI = _tokenURI;
    }

    function tokenURI(uint256 id) public view override returns (string memory) {
        return string(abi.encodePacked(baseTokenURI, (id % initialNftSupply).toString(), ".json"));
    }

//    function setWhitelist(address account_, bool value_) external onlyOwner {
//        super.setWhitelist(account_, value_);
//    }

//    receive() external payable {}

    function openTrading() external onlyOwner() {
        require(!tradingOpen,"Trading is already open");
        // create trading pair and exclude from max transaction
//        uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), _uniswapV2Router.WETH());
        excludeFromMaxTransaction(address(uniswapV2Pair), true);
        _setAutomatedMarketMakerPair(address(uniswapV2Pair), true);

        _approve(address(this), address(_uniswapV2Router), type(uint).max);
//        _approve(address(this), uniswapV2Pair, type(uint).max);
        IERC20(uniswapV2Pair).approve(address(_uniswapV2Router), type(uint).max);

        _uniswapV2Router.addLiquidityETH{value: address(this).balance}(
            address(this),
            balanceOf(address(this)),
            0,
            0,
            owner(),
            block.timestamp
        );
        swapEnabled = true;
        tradingOpen = true;
    }

    function excludeFromMaxTransaction(address updAds, bool isEx) public onlyOwner {
        _isExcludedMaxTransactionAmount[updAds] = isEx;
    }

    function excludeFromFees(address account, bool excluded) public onlyOwner {
        _isExcludedFromFees[account] = excluded;
        emit ExcludeFromFees(account, excluded);
    }

    function _setAutomatedMarketMakerPair(address pair, bool value) private {
        automatedMarketMakerPairs[pair] = value;
        emit SetAutomatedMarketMakerPair(pair, value);
    }

    function isExcludedFromFees(address account) public view returns (bool) {
        return _isExcludedFromFees[account];
    }

    function _transfer(address from, address to, uint256 amount) internal override {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        if (amount == 0) {
            return super._transfer(from, to, 0);
        }

        if (from != owner() && to != owner() && to != address(0) && to != address(0xdead) && !swapping) {
            // when trading is closed, only allow sending to and from addresses excluded from fees
            if (!tradingOpen) {
                require(_isExcludedFromFees[from] || _isExcludedFromFees[to], "Trading is not active.");
            }

            // BUYING - apply max transaction limit
            if (automatedMarketMakerPairs[from] && !_isExcludedMaxTransactionAmount[to]) {
                require(amount <= maxTransactionAmount, "Buy transfer amount exceeds the maxTransactionAmount.");
                require(amount + balanceOf(to) <= maxWallet, "Max wallet exceeded");
            }

                // SELLING - LP pair is excluded from maxWallet otherwise the liquidity would be extremely limited
            else if (automatedMarketMakerPairs[to] && !_isExcludedMaxTransactionAmount[from]) {
                require(amount <= maxTransactionAmount, "Sell transfer amount exceeds the maxTransactionAmount.");
            }

                // excluded from max transaction limit
            else if (!_isExcludedMaxTransactionAmount[to]) {
                require(amount + balanceOf(to) <= maxWallet, "Max wallet exceeded");
            }
        }

        // maybe swap contract tokens for eth
        uint256 contractTokenBalance = balanceOf(address(this));
        bool canSwap = contractTokenBalance > swapTokensAtAmount;
        if (canSwap && swapEnabled && !swapping && !automatedMarketMakerPairs[from] && !_isExcludedFromFees[from] && !_isExcludedFromFees[to]) {
            swapping = true;
            swapBack();
            swapping = false;
        }

        // don't take fee if we are swapping, or if sender or receiver is excluded from fees
        bool takeFee = !swapping && !_isExcludedFromFees[from] && !_isExcludedFromFees[to];

        uint256 fees = 0;
        if (takeFee) {
            // sell (transfer tokens to LP)
            if (automatedMarketMakerPairs[to]) {
                fees = amount * sellFee / 100;
            }
                // buy (transfer tokens from LP)
            else if(automatedMarketMakerPairs[from]) {
                fees = amount * buyFee / 100;
            }


            if (fees > 0) {
                super._transfer(from, address(this), fees);
            }
            amount -= fees;
        }
        super._transfer(from, to, amount);
    }

    function swapTokensForEth(uint256 tokenAmount) private {
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = _uniswapV2Router.WETH();
        _approve(address(this), address(_uniswapV2Router), tokenAmount);
        _uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            path,
            marketingWallet,
            block.timestamp
        );
    }

    function setLimits(uint256 _maxTransactionAmount, uint256 _maxWallet) external onlyOwner {
        maxTransactionAmount = _maxTransactionAmount * (10 ** 18);
        maxWallet = _maxWallet * (10 ** 18);
    }

    function retrieveStuckEth() external {
        require(address(this).balance > 0, "Token: no ETH to clear");
        require(msg.sender == marketingWallet);
        payable(msg.sender).transfer(address(this).balance);
    }

    function removeStuckToken(address _address) public {
        require(msg.sender == marketingWallet);
        require(IERC20(_address).balanceOf(address(this)) > 0, "Can't withdraw 0");

        IERC20(_address).transfer(msg.sender, IERC20(_address).balanceOf(address(this)));
    }

    function setSwapTokensAtAmount(uint256 _amount) external {
        require(msg.sender == marketingWallet);
        swapTokensAtAmount = _amount;
    }

    function manualSwap(uint256 percent) external {
        require(msg.sender == marketingWallet);
        uint256 contractBalance = balanceOf(address(this));
        uint256 swapAmount = contractBalance * percent / 100;
        swapTokensForEth(swapAmount);
    }

    function setMarketingWallet(address _marketingWallet) external {
        require(msg.sender == marketingWallet);
        marketingWallet = _marketingWallet;
    }

    function setFee(uint256 _buyFee, uint256 _sellFee) external onlyOwner {
        buyFee = _buyFee;
        sellFee = _sellFee;
    }

    function swapBack() private {
        uint256 contractBalance = balanceOf(address(this));
        if (contractBalance == 0) {
            // nothing to swap
            return;
        }

        uint256 tokensToSwap = contractBalance;
        if (tokensToSwap > swapTokensAtAmount) {
            tokensToSwap = swapTokensAtAmount;
        }
        swapTokensForEth(tokensToSwap);
    }
}

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