code: def test_opaque():
      alpha = hopper("P").convert("PA").getchannel("A")
  
      solid = Image.new("L", (128, 128), 255)
      assert_image_equal(alpha, solid)
  
imports: from __future__ import annotations
  import pytest
  from PIL import Image
  from .helper import assert_image, assert_image_equal, assert_image_similar, hopper
label_desc: Use image node_id 8 for calling a global function with example usage: test_opaque() without return types