code: def test_listdir():
      DIR = PATH_TO_MEDIA_FILES
  
      dir_list = caer.path.listdir(
          DIR, recursive=True, use_fullpath=True
      )
  
      assert dir_list is not None
      assert (
          len(dir_list) == 7
      )  # There are 3 images, 3 videos and 1 README.md in tests/media
  
      for i in dir_list:
          assert os.path.exists(i)
  
file_path: caer/tests/path/test_paths.py
imports: import os
  import caer
label_desc: Use image node_id 3 for calling a global function with example usage: test_listdir() without return types