code: def test_webcam():
      good_paths = ["<video0>", "<video42>"]
      for path in good_paths:
          # regression test for https://github.com/imageio/imageio/issues/676
          with iio3.imopen(path, "r", plugin="FFMPEG"):
              pass
  
          try:
              iio.read(path, format="ffmpeg")
          except IndexError:
              # IndexError should be raised when
              # path string is good but camera doesnt exist
              continue
  
      bad_paths = ["<videof1>", "<video0x>", "<video>"]
      for path in bad_paths:
          with pytest.raises(ValueError):
              iio.read(path)
  
imports: import gc
  import os
  import platform
  import sys
  import threading
  import time
  import warnings
  from io import BytesIO
  from pathlib import Path
  import imageio.plugins
  import imageio.v2
  import imageio.v3
  import numpy
  import pytest
  from imageio import core
  from imageio.core import IS_PYPY
  from conftest import deprecated_test
label_desc: Use image node_id 19 for calling a global function with example usage: test_webcam() without return types