text: from moviepy.decorators import audio_video_fx
  
  
  @audio_video_fx
  def volumex(clip, factor):
      """ Returns a clip with audio volume multiplied by the
      value `factor`. Can be applied to both audio and video clips.
  
      This effect is loaded as a clip method when you use moviepy.editor,
      so you can just write ``clip.volumex(2)``
  
      Examples
      ---------
  
      >>> newclip = volumex(clip, 2.0) # doubles audio volume
      >>> newclip = clip.fx( volumex, 0.5) # half audio, use with fx
      >>> newclip = clip.volumex(2) # only if you used "moviepy.editor"
      """
      return clip.fl(lambda gf, t: factor * gf(t),
                     keep_duration=True)
  
  