def get_families(self):
url_path = '<STR_LIT>'<EOL>return objects.FamilyList(self._get_request(url_path))<EOL>
Gets all families.

        In plenary mode, the returned list contains all known families
        or an error results. Otherwise, the returned list may contain
        only those families that are accessible through this session.

        return: (osid.relationship.FamilyList) - a list of families
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        *compliance: mandatory -- This method must be implemented.*