code: def test_reducing_gap_for_DCT_scaling():
      with Image.open("Tests/images/hopper.jpg") as ref:
          # thumbnail should call draft with reducing_gap scale
          ref.draft(None, (18 * 3, 18 * 3))
          ref = ref.resize((18, 18), Image.Resampling.BICUBIC)
  
          with Image.open("Tests/images/hopper.jpg") as im:
              im.thumbnail(
                  (18, 18), Image.Resampling.BICUBIC, reducing_gap=3.0
              )
  
              assert_image_similar(ref, im, 1.4)
  
file_path: pillow/Tests/test_image_thumbnail.py
imports: from __future__ import annotations
  import pytest
  from PIL import Image
  from .helper import assert_image_equal, assert_image_similar, fromstring, hopper, skip_unless_feature, tostring
label_desc: Use image node_id 10 for calling a global function with example usage: test_reducing_gap_for_DCT_scaling() without return types