code: def backends():
      backends_ = ["video_reader"]
      if av is not None:
          backends_.append("pyav")
      return backends_
  
file_path: vision/test/test_videoapi.py
imports: import collections
  import os
  import urllib
  import pytest
  import torch
  import torchvision
  from pytest import approx
  from torchvision.datasets.utils import download_url
  from torchvision.io import _HAS_VIDEO_OPT, VideoReader
label_desc: Use image node_id 1 for calling a global function with example usage: backends() and returns: backends_