@utilities.arguments_not_none<EOL><INDENT>def search_among_relationships(self, relationship_ids):<DEDENT>
self._id_list = relationship_ids<EOL>
Execute this search among the given list of relationships.

        arg:    relationship_ids (osid.id.IdList): list of relationships
        raise:  NullArgument - ``relationship_ids`` is ``null``
        *compliance: mandatory -- This method must be implemented.*