isCoinBase method
Implementation
bool isCoinBase() {
var zeroHash = List<int>.generate(32, (i)=>0);
return (ListEquality().equals(HEX.decode(_prevTxnId!), zeroHash)) &&
((_prevTxnOutputIndex! & 0xFFFFFFFF) == 0xFFFFFFFF); // -1 but all is serialized to the wire as unsigned int.
}