code: def from_json(cls, json):
      
      return cls(json[cls.BLOB_KEY_PARAM],
                 json[cls.START_INDEX_PARAM],
                 json[cls.END_INDEX_PARAM])
docs: Creates an instance of the InputReader for the given input shard state.
  
      Args:
        json: The InputReader state as a dict-like object.
  
      Returns:
        An instance of the InputReader configured using the values of json.