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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 enqueue(self, stream_url, offset=0, opaque_token=None):
 """Adds stream to the queue. Does not impact the currently playing stream."""

        directive = self._play_directive('ENQUEUE')
        audio_item = self._audio_item(stream_url=stream_url,
                                      offset=offset,
                                      push_buffer=False,
                                      opaque_token=opaque_token)
        audio_item['stream']['expectedPreviousToken'] = current_stream.token

        directive['audioItem'] = audio_item
        self._response['directives'].append(directive)
        return self