code: def test_list_files(self):
      from sahi.utils.file import list_files
  
      directory = "tests/data/coco_utils/"
      filepath_list = list_files(
          directory, contains=["json"], verbose=False
      )
      self.assertEqual(len(filepath_list), 11)
  
imports: import unittest
label_desc: Use image node_id 1 for calling the TestFileUtils obj's underlying member method code with example usage: obj.test_list_files() without return types