How to expect a failure in robot framework in Python?

We use robot framework at work to do some automated testing, and I need to add a few tests. This format is already in the repo, I cannot change anything drastically.

I am using a keywords file that looks like this:

#!/usr/bin/env python3# -*- coding: utf-8 -*-from robot.api.deco import keywordclass testkeywords(object):""""""   def __init__(self):      pass   @keyword('I compare ${first_number} with ${second_number}')   def compare(self, first_number, second_number):      if (int(first_number) != int(second_number)):         raise ValueError('Numbers are not the same.')

The .robot file has two tests, one that passes and one that fails:

*** Settings ***Library         testkeywords.py*** Variables ***${num_a}       5${num_b}       6*** Test Cases ***Compare same numbers   I compare ${num_a} with ${num_a}Compare different numbers   I compare ${num_a} with ${num_b}

The Compare different numbers test fails as expected, but it's still a FAIL. How can I set it to expect a failure and hence pass the keyword?