Verify OP_RETURN field in transaction
    :param signed_hextx:
    :param op_return_value:
    :return:

def verify_transaction(signed_hextx, op_return_value):
    """
    Verify OP_RETURN field in transaction
    :param signed_hextx:
    :param op_return_value:
    :return:
    """
    logging.info('verifying op_return value for transaction')
    op_return_hash = signed_hextx[-72:-8]
    result = (op_return_value == op_return_hash)
    if not result:
        error_message = 'There was a problem verifying the transaction'
        raise UnverifiedTransactionError(error_message)
    logging.info('verified OP_RETURN')