code: def test_st_help_no_arg(self):
      actual = _get_variable_name_from_code_str("st.help()")
      self.assertEqual(actual, None)
  
imports: import inspect
  import sys
  import unittest
  from unittest.mock import patch
  import numpy
  import pytest
  import streamlit
  from streamlit.elements.doc_string import _get_variable_name_from_code_str
  from tests.delta_generator_test_case import DeltaGeneratorTestCase
label_desc: Use image node_id 1 for calling the GetVariableNameFromCodeStrTest obj's underlying member method code with example usage: obj.test_st_help_no_arg() without return types