code: def test_native_pixformat_reading(test_images):
      frames = iio.imread(
          test_images / "cockatoo.mp4",
          index=5,
          plugin="pyav",
          format=None,
      )
  
      # cockatoo.mp4 uses YUV444p
      assert frames.shape == (3, 720, 1280)
  
imports: import io
  import warnings
  from contextlib import ExitStack
  from pathlib import Path
  import numpy
  import pytest
  from conftest import IS_PYPY
  import imageio.v3
  from av.video.format import names
  from imageio.plugins.pyav import _format_to_dtype
label_desc: Use image node_id 18 for calling a global function with example usage: test_native_pixformat_reading(test_images) without return types