docs: def add_intersecting(self, division, intersection=None, symm=True):
          """
          Adds paired relationships between intersecting divisions.
  
          Optional intersection represents the portion of the area of the related
          division intersecting this division. You can only specify an
          intersection on one side of the relationship when adding a peer.
          """
          relationship, created = IntersectRelationship.objects.update_or_create(
              from_division=self,
              to_division=division,
              defaults={"intersection": intersection},
          )
          if symm:
              division.add_intersecting(self, None, False)
          return relationship