'Marks multiple urns (and their children) for deletion.'

def MultiMarkForDeletion(self, urns):

    all_children_urns = self.RecursiveMultiListChildren(urns)
    urns += list(itertools.chain.from_iterable(all_children_urns.values()))
    self._urns_for_deletion.update(urns)
    for obj in self.MultiOpen(urns):
        obj.OnDelete(deletion_pool=self)
