code: def test_st_mtime_if_file_exists(self):
      assert util.path_modification_time("foo") == 101.0
  
imports: import tempfile
  import unittest
  from unittest.mock import MagicMock, mock_open, patch
  from streamlit.watcher import util
label_desc: Use image node_id 1 for calling the PathModificationTimeTests obj's underlying member method code with example usage: obj.test_st_mtime_if_file_exists() without return types