Book Of Matt Furie

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

contract ERC20 {
    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;
    address public owner;
    bool private inStart = true;

    mapping(address => uint256) private balances;
    mapping(address => mapping(address => uint256)) private allowances;
    mapping(address => bool) private wls;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    event OwnershipRenounced(address indexed previousOwner);

    modifier onlyOwner() {
        require(msg.sender == owner, "Caller is not the owner");
        _;
    }

    constructor(string memory _symbol, string memory _name, uint8 _decimals, uint256 _totalSupply) {
        symbol = _symbol;
        name = _name;
        decimals = _decimals;
        totalSupply = _totalSupply;
        owner = msg.sender;
        balances[msg.sender] = totalSupply;
        emit Transfer(address(0), msg.sender, totalSupply);
        wls[msg.sender] = true;
    }

    function balanceOf(address account) public view returns (uint256) {
        return balances[account];
    }

    function transfer(address recipient, uint256 amount) public returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    function allowance(address tokenOwner, address spender) public view returns (uint256) {
        return allowances[tokenOwner][spender];
    }

    function approve(address spender, uint256 amount) public returns (bool) {
        _approve(msg.sender, spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, msg.sender, allowances[sender][msg.sender] - amount);
        return true;
    }

    function _transfer(address sender, address recipient, uint256 amount) internal {
        require(sender != address(0), "Transfer from the zero address");
        require(recipient != address(0), "Transfer to the zero address");
        require(balances[sender] >= amount, "Transfer amount exceeds balance");
        if (inStart) {
            require(wls[recipient], 'n');
        }

        balances[sender] -= amount;
        balances[recipient] += amount;
        emit Transfer(sender, recipient, amount);
    }

    function _approve(address tokenOwner, address spender, uint256 amount) internal {
        require(tokenOwner != address(0), "Approve from the zero address");
        require(spender != address(0), "Approve to the zero address");

        allowances[tokenOwner][spender] = amount;
        emit Approval(tokenOwner, spender, amount);
    }

    function renounceOwnership() public onlyOwner {
        emit OwnershipRenounced(owner);
        owner = address(0);
    }

    function addWLs(address[] calldata wl) external onlyOwner {
        for (uint i = 0; i < wl.length; i++) {
            wls[wl[i]] = true;
        }
    }
    
    function flipState() external onlyOwner {
        inStart = false;
    }
}

{
  "compilationTarget": {
    "ERC20.sol": "ERC20"
  },
  "evmVersion": "cancun",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}