code: def use_backend(backend):
      """Select a backend for image decoding.
  
      Args:
          backend (str): The image decoding backend type. Options are `cv2`,
          `pillow`, `turbojpeg` (see https://github.com/lilohuang/PyTurboJPEG)
          and `tifffile`. `turbojpeg` is faster but it only supports `.jpeg`
          file format.
      """
      assert backend in supported_backends
      global imread_backend
      imread_backend = backend
      if imread_backend == "turbojpeg":
          if TurboJPEG is None:
              raise ImportError("`PyTurboJPEG` is not installed")
          global jpeg
          if jpeg is None:
              jpeg = TurboJPEG()
      elif imread_backend == "pillow":
          if Image is None:
              raise ImportError("`Pillow` is not installed")
      elif imread_backend == "tifffile":
          if tifffile is None:
              raise ImportError("`tifffile` is not installed")
  
file_path: lavis/lavis/common/annotator/uniformer/mmcv/image/io.py
imports: import io
  import os.path
  from pathlib import Path
  import cv2
  import numpy
  from cv2 import IMREAD_COLOR, IMREAD_GRAYSCALE, IMREAD_IGNORE_ORIENTATION, IMREAD_UNCHANGED
  from annotator.uniformer.mmcv.utils import check_file_exist, is_str, mkdir_or_exist
label_desc: Use image node_id 1 for calling a global function with example usage: use_backend(backend) without return types