code: def _clear_audio_file(self, audio_file):
          
          self._step_begin(u"clear audio file")
          audio_file.clear_data()
          audio_file = None
          self._step_end()
docs: Clear audio from memory.
  
          :param audio_file: the object to clear
          :type  audio_file: :class:`~aeneas.audiofile.AudioFile`