public void TransferFrom(Address from, Address to, ulong amount)
{
var allowance = Allowances.GetAllowance(from, Api.GetTransaction().From);
Api.Assert(allowance > amount, "Insufficient allowance.");
DoTransfer(from, to, amount);
Allowances.Reduce(from, amount);
}
public ulong Allowance(Address owner, Address spender)
{
return(Allowances.GetAllowance(owner, spender));
}