code: def all(cls):
          
          for result in cls._query.all_index():
              yield cls.load(result, convert_key=False)
docs: Return an iterator that successively yields saved model
          instances. Models are saved in an unordered :py:class:`Set`,
          so the iterator will return them in arbitrary order.
  
          Example::
  
              for note in Note.all():
                  print note.content
  
          To return models in sorted order, see :py:meth:`Model.query`.
          Example returning all records, sorted newest to oldest::
  
              for note in Note.query(order_by=Note.timestamp.desc()):
                  print note.timestamp, note.content