code: def _synthesize(self, text_file):
          
          handler, path = gf.tmp_file(suffix=u".wav", root=self.rconf[RuntimeConfiguration.TMP_PATH])
          result = self.synthesizer.synthesize(text_file, path)
          return (handler, path, result[0], self.synthesizer.output_audio_format)
docs: Synthesize text into a WAVE file.
  
          Return a tuple consisting of:
  
          1. the handler of the generated audio file
          2. the path of the generated audio file
          3. the list of anchors, that is, a list of floats
             each representing the start time of the corresponding
             text fragment in the generated wave file
             ``[start_1, start_2, ..., start_n]``
          4. a tuple describing the format of the audio file
  
          :param text_file: the text to be synthesized
          :type  text_file: :class:`~aeneas.textfile.TextFile`
          :rtype: tuple (handler, string, list)