def symmetric_difference_update(self, other):
        r
        other = self._as_multiset(other)
        elements = set(self.distinct_elements()) | set(other.distinct_elements())
        for element in elements:
            multiplicity = self[element]
            other_count = other[element]
            self[element] = (multiplicity - other_count if multiplicity > other_count else other_count - multiplicity)