function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}


contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

   
  modifier onlyPayloadSize(uint size) {
     require(msg.data.length >= size + 4);
     _;
  }