class_docstr: Credentials Class Unittest class.
docstr: Test Credentials.get_current.
code: def test_Credentials_get_current(self):
      """Test Credentials.get_current."""
  
      Credentials._singleton = None
      c = Credentials.get_current()
  
      self.assertEqual(Credentials._singleton, c)
  
imports: import os
  import textwrap
  import unittest
  from pathlib import Path
  from unittest.mock import MagicMock, call, mock_open, patch
  import pytest
  import requests_mock
  from testfixtures import tempdir
  from streamlit import file_util
  from streamlit.runtime.credentials import Credentials, _Activation, _verify_email, email_prompt
label_desc: Use image node_id 4 for calling the CredentialsClassTest obj's underlying member method code with example usage: obj.test_Credentials_get_current() without return types