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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def to_json(self):
 """Returns an json-compatible input shard spec for remaining inputs."""

    new_pos = self._blob_reader.tell()
    if self._has_iterated:
      new_pos -= 1
    return {self.BLOB_KEY_PARAM: self._blob_key,
            self.INITIAL_POSITION_PARAM: new_pos,
            self.END_POSITION_PARAM: self._end_position}