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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 close(self):
 """Send a close message to the external process and join it."""

    try:
      self._conn.send((self._CLOSE, None))
      self._conn.close()
    except IOError:
      # The connection was already closed.
      pass
    self._process.join()