contract ERC20 { 
    function transfer(address receiver, uint amount) public ;
    function transferFrom(address sender, address receiver, uint amount) public returns(bool success); // do token.approve on the ICO contract
    function balanceOf(address _owner) constant public returns (uint256 balance);
}
function balanceOf(address _owner) constant public returns (uint256 balance);
// do token.approve on the ICO contract