code: def delete_relationship(self, relationship_id=None):
          
          if relationship_id is None:
              raise NullArgument()
          if not isinstance(relationship_id, Id):
              raise InvalidArgument('argument type is not an osid Id')
  
          url_path = ('/handcar/services/relationship/families/' +
                      self._catalog_idstr + '/relationships/' +
                      str(relationship_id))
          result = self._delete_request(url_path)
          return objects.Relationship(result)
docs: Deletes a ``Relationship``.
  
          arg:    relationship_id (osid.id.Id): the ``Id`` of the
                  ``Relationship`` to remove
          raise:  NotFound - ``relationship_id`` not found
          raise:  NullArgument - ``relationship_id`` is ``null``
          raise:  OperationFailed - unable to complete request
          raise:  PermissionDenied - authorization failure
          *compliance: mandatory -- This method must be implemented.*