code: def test_subfx(util):
      clip = VideoFileClip("media/big_buck_bunny_0_30.webm").subclip(
          0, 1
      )
      transform = lambda c: multiply_speed(c, 0.5)
      new_clip = clip.subfx(transform, 0.5, 0.8)
      location = os.path.join(util.TMP_DIR, "subfx.mp4")
      new_clip.write_videofile(location)
      assert os.path.isfile(location)
  
imports: import copy
  import os
  import numpy
  from PIL import Image
  import pytest
  from moviepy.audio.AudioClip import AudioClip
  from moviepy.audio.io.AudioFileClip import AudioFileClip
  from moviepy.tools import convert_to_seconds
  from moviepy.video.compositing.CompositeVideoClip import CompositeVideoClip
  from moviepy.video.fx.mask_color import mask_color
  from moviepy.video.fx.multiply_speed import multiply_speed
  from moviepy.video.io.VideoFileClip import VideoFileClip
  from moviepy.video.VideoClip import BitmapClip, ColorClip, ImageClip, VideoClip
label_desc: Use image node_id 19 for calling a global function with example usage: test_subfx(util) without return types