vrfInOut_ method
Implementation
VRFInOut vrfInOut_(MerlinTranscript script) {
  final publicHashPoint = publicKey().vrfHash(script);
  final mul = Ed25519Utils.mul(
      Ed25519Utils.scalarReduceConst(key()), publicHashPoint.toBytes());
  final p = RistrettoPoint.fromEdwardBytes(mul);
  return VRFInOut._(publicHashPoint.toBytes(), p.toBytes());
}