@classmethod
  def from_json(cls, json):
    key_range_iter_cls = _KEY_RANGE_ITERATORS[json["key_range_iter_cls"]]
    obj = cls(key_ranges.KeyRangesFactory.from_json(json["key_ranges"]),
              model.QuerySpec.from_json(json["query_spec"]),
              key_range_iter_cls)

    current_iter = None
    if json["current_iter"]:
      current_iter = key_range_iter_cls.from_json(json["current_iter"])
    # pylint: disable=protected-access
    obj._current_iter = current_iter
    return obj


# A map from class name to class of all RangeIterators.
Inherit doc.
dataset/ETHPy150Open GoogleCloudPlatform/appengine-mapreduce/python/src/mapreduce/datastore_range_iterators.py/_KeyRangesIterator.from_json