code: def setUp(self) -> None:
      # st.secrets modifies os.environ, so we save it here and
      # restore in tearDown.
      self._prev_environ = dict(os.environ)
      self.secrets = Secrets(MOCK_SECRETS_FILE_LOC)
  
imports: import os
  import tempfile
  import unittest
  from collections.abc import Mapping
  from collections.abc import MutableMapping
  from typing import Mapping, MutableMapping
  from unittest.mock import MagicMock, mock_open, patch
  from parameterized import parameterized
  from toml import TomlDecodeError
  from streamlit.runtime.secrets import SECRETS_FILE_LOCS, AttrDict, Secrets
  from tests.exception_capturing_thread import call_on_threads
label_desc: Use image node_id 1 for calling the SecretsThreadingTests obj's underlying member method code with example usage: obj.setUp() without return types