def _extract_more_comments(tree):
        """Return a list of MoreComments objects removed from tree."""
        more_comments = []
        queue = [(None, x) for x in tree]
        while len(queue) > 0:
            parent, comm = queue.pop(0)
            if isinstance(comm, MoreComments):
                heappush(more_comments, comm)
                if parent:
                    parent.replies.remove(comm)
                else:
                    tree.remove(comm)
            else:
                for item in comm.replies:
                    queue.append((comm, item))
        return more_comments
Return a list of MoreComments objects removed from tree.