def add_intersecting(self, division, intersection=None, symm=True):
relationship, created = IntersectRelationship.objects.update_or_create(<EOL>from_division=self,<EOL>to_division=division,<EOL>defaults={"<STR_LIT>": intersection},<EOL>)<EOL>if symm:<EOL><INDENT>division.add_intersecting(self, None, False)<EOL><DEDENT>return relationship<EOL>
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.