code: def audio_fadein(clip, duration):
      """Return an audio (or video) clip that is first mute, then the
      sound arrives progressively over ``duration`` seconds.
  
      Parameters
      ----------
  
      duration : float
        How long does it take for the sound to return to its normal level.
  
      Examples
      --------
  
      >>> clip = VideoFileClip("media/chaplin.mp4")
      >>> clip.fx(audio_fadein, "00:00:06")
      """
      get_factor = (
          _mono_factor_getter()
          if clip.nchannels == 1
          else _stereo_factor_getter(clip.nchannels)
      )
  
      return clip.transform(
          lambda get_frame, t: get_factor(t, duration) * get_frame(t),
          keep_duration=True,
      )
  
imports: import numpy
  from moviepy.decorators import audio_video_fx, convert_parameter_to_seconds
label_desc: Use image node_id 3 for calling a global function with example usage: audio_fadein(clip, duration) and returns: clip