code: def count(self):
          "Return how many nodes this contains, including self."
          if self._nodes is None:
              return 1
          return sum(i.count() for i in self._nodesf count(self):
          "Return how many nodes this contains, including self."
          if self._nodes is None:
              return 1
          return sum(i.count() for i in self._nodes)
docs: Return how many nodes this contains, including self.