creation_sourcecode: // SPDX-License-Identifier: MIT
  // Compatible with OpenZeppelin Contracts ^5.0.0
  pragma solidity ^0.8.20;
  
  interface IERC20Errors {
      error ERC20InsufficientBalance(address sender, uint256 balance, uint256 needed);
      error ERC20InvalidSender(address sender);
      error ERC20InvalidReceiver(address receiver);
      error ERC20InsufficientAllowance(address spender, uint256 allowance, uint256 needed);
      error ERC20InvalidApprover(address approver);
      error ERC20InvalidSpender(address spender);
  }
  
  interface IERC721Errors {
      error ERC721InvalidOwner(address owner);
      error ERC721NonexistentToken(uint256 tokenId);
      error ERC721IncorrectOwner(address sender, uint256 tokenId, address owner);
      error ERC721InvalidSender(address sender);
      error ERC721InvalidReceiver(address receiver);
      error ERC721InsufficientApproval(address operator, uint256 tokenId);
      error ERC721InvalidApprover(address approver);
      error ERC721InvalidOperator(address operator);
  }
  
  interface IERC1155Errors {
      error ERC1155InsufficientBalance(address sender, uint256 balance, uint256 needed, uint256 tokenId);
      error ERC1155InvalidSender(address sender);
      error ERC1155InvalidReceiver(address receiver);
      error ERC1155MissingApprovalForAll(address operator, address owner);
      error ERC1155InvalidApprover(address approver);
      error ERC1155InvalidOperator(address operator);
      error ERC1155InvalidArrayLength(uint256 idsLength, uint256 valuesLength);
  }
  
  abstract contract Context {
      function _msgSender() internal view virtual returns (address) {
          return msg.sender;
      }
      function _msgData() internal view virtual returns (bytes calldata) {
          return msg.data;
      }
      function _contextSuffixLength() internal view virtual returns (uint256) {
          return 0;
      }
  }
  
  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);
  }
  
  interface IERC20Metadata is IERC20 {
      function name() external view returns (string memory);
      function symbol() external view returns (string memory);
      function decimals() external view returns (uint8);
  }
  
  abstract contract ERC20 is Context, IERC20, IERC20Metadata, IERC20Errors {
      mapping(address account => uint256) private _balances;
  
      mapping(address account => mapping(address spender => uint256)) private _allowances;
  
      uint256 private _totalSupply;
  
      string private _name;
      string private _symbol;
      constructor(string memory name_, string memory symbol_) {
          _name = name_;
          _symbol = symbol_;
      }
      function name() public view virtual returns (string memory) {
          return _name;
      }
      function symbol() public view virtual returns (string memory) {
          return _symbol;
      }
      function decimals() public view virtual returns (uint8) {
          return 18;
      }
      function totalSupply() public view virtual returns (uint256) {
          return _totalSupply;
      }
      function balanceOf(address account) public view virtual returns (uint256) {
          return _balances[account];
      }
      function transfer(address to, uint256 value) public virtual returns (bool) {
          address owner = _msgSender();
          _transfer(owner, to, value);
          return true;
      }
      function allowance(address owner, address spender) public view virtual returns (uint256) {
          return _allowances[owner][spender];
      }
      function approve(address spender, uint256 value) public virtual returns (bool) {
          address owner = _msgSender();
          _approve(owner, spender, value);
          return true;
      }
      function transferFrom(address from, address to, uint256 value) public virtual returns (bool) {
          address spender = _msgSender();
          _spendAllowance(from, spender, value);
          _transfer(from, to, value);
          return true;
      }
      function _transfer(address from, address to, uint256 value) internal {
          if (from == address(0)) {
              revert ERC20InvalidSender(address(0));
          }
          if (to == address(0)) {
              revert ERC20InvalidReceiver(address(0));
          }
          _update(from, to, value);
      }
      function _update(address from, address to, uint256 value) internal virtual {
          if (from == address(0)) {
              // Overflow check required: The rest of the code assumes that totalSupply never overflows
              _totalSupply += value;
          } else {
              uint256 fromBalance = _balances[from];
              if (fromBalance < value) {
                  revert ERC20InsufficientBalance(from, fromBalance, value);
              }
              unchecked {
                  // Overflow not possible: value <= fromBalance <= totalSupply.
                  _balances[from] = fromBalance - value;
              }
          }
  
          if (to == address(0)) {
              unchecked {
                  // Overflow not possible: value <= totalSupply or value <= fromBalance <= totalSupply.
                  _totalSupply -= value;
              }
          } else {
              unchecked {
                  // Overflow not possible: balance + value is at most totalSupply, which we know fits into a uint256.
                  _balances[to] += value;
              }
          }
  
          emit Transfer(from, to, value);
      }
      function _mint(address account, uint256 value) internal {
          if (account == address(0)) {
              revert ERC20InvalidReceiver(address(0));
          }
          _update(address(0), account, value);
      }
      function _burn(address account, uint256 value) internal {
          if (account == address(0)) {
              revert ERC20InvalidSender(address(0));
          }
          _update(account, address(0), value);
      }
      function _approve(address owner, address spender, uint256 value) internal {
          _approve(owner, spender, value, true);
      }
      function _approve(address owner, address spender, uint256 value, bool emitEvent) internal virtual {
          if (owner == address(0)) {
              revert ERC20InvalidApprover(address(0));
          }
          if (spender == address(0)) {
              revert ERC20InvalidSpender(address(0));
          }
          _allowances[owner][spender] = value;
          if (emitEvent) {
              emit Approval(owner, spender, value);
          }
      }
      function _spendAllowance(address owner, address spender, uint256 value) internal virtual {
          uint256 currentAllowance = allowance(owner, spender);
          if (currentAllowance != type(uint256).max) {
              if (currentAllowance < value) {
                  revert ERC20InsufficientAllowance(spender, currentAllowance, value);
              }
              unchecked {
                  _approve(owner, spender, currentAllowance - value, false);
              }
          }
      }
  }
  
  contract Bitgold is ERC20 {
      constructor() ERC20("Bitgold Token", "BTGT") {
          _mint(msg.sender, 200000000 * 10 ** decimals());
      }
  }