code: def test_writable_output():
      rng = np.random.default_rng()
      img = rng.integers(0, 255, (128, 128), dtype=np.uint8)
      buffer = iio.imwrite("<bytes>", img, extension=".png")
  
      frame = iio.imread(buffer, plugin="pillow")
      assert frame.flags["WRITEABLE"]
  
      frame = iio.imread(
          buffer, writeable_output=False, plugin="pillow"
      )
      assert not frame.flags["WRITEABLE"]
  
imports: import io
  import os
  from pathlib import Path
  import imageio.v3
  import numpy
  import pytest
  from imageio.core.request import InitializationError, Request
  from imageio.core.v3_plugin_api import PluginV3
  from imageio.plugins.pillow import PillowPlugin
  from PIL import Image, ImageSequence, ImageOps, __version__
label_desc: Use image node_id 43 for calling a global function with example usage: test_writable_output() without return types