def remove_edges_from(self, ebunch):
        """Version of remove_edges_from that's much like normal networkx but only
        deletes once, since the database doesn't keep separate adj and
        succ mappings

        """
        for e in ebunch:
            (u, v) = e[:2]
            if u in self.succ and v in self.succ[u]:
                del self.succ[u][v]
Version of remove_edges_from that's much like normal networkx but only
        deletes once, since the database doesn't keep separate adj and
        succ mappings