contract ERC20Interface {
    // Get the total token supply
    function totalSupply() public constant returns (uint256 supply);

    // Get the account balance of another a ccount with address _owner
    function balanceOf(address _owner) public constant returns (uint256 balance);

    // Send _value amount of tokens to address _to
    function transfer(address _to, uint256 _value) public returns (bool success);

    // Send _value amount of tokens from address _from to address _to
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);

    // Allow _spender to withdraw from your account, multiple times, up to the _value amount.
    // If this function is called again it overwrites the current allowance with _value.
    // this function is required for some DEX functionality
    function approve(address _spender, uint256 _value) public returns (bool success);

    // Returns the amount which _spender is still allowed to withdraw from _owner
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining);

    // Triggered when tokens are transferred.
    event Transfer(address indexed _from, address indexed _to, uint256 _value);

    // Triggered whenever approve(address _spender, uint256 _value) is called.
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}
function approve(address _spender, uint256 _value) public returns (bool success);
// Allow _spender to withdraw from your account, multiple times, up to the _value amount.
// If this function is called again it overwrites the current allowance with _value.
// this function is required for some DEX functionality