How to use the drama.Rivalry function in drama

def _excavate_rivalries(self):
        """Recognize cases where mutual animosity exists between a pair of characters."""
        rivalries = []
        for person in self.simulation.town.residents:
            for other_person in person.relationships:
                if person.dislikes(other_person) and other_person.dislikes(person):
                    subjects = (person, other_person)
                    if not any(r for r in self.rivalries if set(r.subjects) == set(subjects)):
                        rivalries.append(Rivalry(subjects=subjects))
        return rivalries