Yield all power nodes containing (power) node of given *name*.

        If *directly* is True, will only yield the direct parent of given name.

def powernodes_containing(self, name, directly=False) -> iter:
        """Yield all power nodes containing (power) node of given *name*.

        If *directly* is True, will only yield the direct parent of given name.

        """
        if directly:
            yield from (node for node in self.all_in(name)
                        if name in self.inclusions[node])
        else:
            # This algorithm is very bad. Inverting the inclusion dict could
            #  be far better.
            @functools.lru_cache(maxsize=self.node_number(count_pnode=True))
            def contains_target(node, target):
                succs = self.inclusions[node]
                if target in succs:
                    return True
                else:
                    return any(contains_target(succ, target) for succ in succs)
            # populate the cache
            for root in self.roots:
                contains_target(root, name)
            # output all that contains target at some level
            yield from (node for node in self.inclusions.keys()
                        if contains_target(node, name))