def run(self, manager):
        """Run this query and returns the resulting BEL graph.

        :param manager: A cache manager
        :rtype: Optional[pybel.BELGraph]
        """
        universe = self._get_universe(manager)
        graph = self.seeding.run(universe)
        return self.pipeline.run(graph, universe=universe)
Run this query and returns the resulting BEL graph.

        :param manager: A cache manager
        :rtype: Optional[pybel.BELGraph]