getTransaction method
Return the Transaction object with the specified hash. @param {string} transactionHash The hash of the transaction to return. @returns {Transaction|null} The Transaction object with the specified hash, or a TransactionError for error.
Implementation
Future<RosettaTransaction> getTransaction(String transactionHash) async {
  try {
    final responseTransactions = await transactionsByHash(transactionHash);
    if (responseTransactions.transactions.isEmpty) {
      throw TransactionError('Transaction not found.', 500);
    }
    return RosettaTransaction(
        responseTransactions.transactions[0].transaction,
        responseTransactions.transactions[0].block_identifier.index);
  } catch (error) {
    //console.log(error);
    rethrow;
  }
}