code: def test_matmul(util):
      clip1 = BitmapClip([["RG"]], fps=1)
      target = BitmapClip([["R", "G"]], fps=1)
      result = clip1 @ 270
      assert result == target
  
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 41 for calling a global function with example usage: test_matmul(util) without return types