code: def test_getbands(self):
      # Assert
      assert hopper("RGB").getbands() == ("R", "G", "B")
      assert hopper("YCbCr").getbands() == ("Y", "Cb", "Cr")
  
imports: import io
  import os
  import shutil
  import sys
  import tempfile
  import pytest
  from PIL import Image, ImageDraw, ImagePalette, UnidentifiedImageError
  from .helper import assert_image_equal, assert_image_equal_tofile, assert_image_similar_tofile, assert_not_all_same, hopper, is_win32, mark_if_feature_version, skip_unless_feature
label_desc: Use image node_id 20 for calling the TestImage obj's underlying member method code with example usage: obj.test_getbands() without return types