contract UpgradedStandardToken_SV is StandardToken_SV{
    // those methods are called by the legacy contract
    // and they must ensure msg.sender to be the contract address
    function transferByLegacy(address from, address to, uint value) public;
    function transferFromByLegacy(address sender, address from, address spender, uint value) public;
    function approveByLegacy(address from, address spender, uint value) public;
}
function transferByLegacy(address from, address to, uint value) public;

// those methods are called by the legacy contract
// and they must ensure msg.sender to be the contract address