signTx method
Implementation
Future<Tx> signTx(
Tx tx, SignerOptions options, List<dynamic> messages) async {
var signDoc = CORE_SIGN.SignDoc(options.chainId!, options.accountNumber!,
options.sequenceNumber!, tx.auth_info,
tx_body: tx.body);
tx.appendSignatures([await createSignature(signDoc, messages)]);
return tx;
}