code: def test_vtk_not_loaded():
      """This test verifies that the vtk module isn't loaded when using vtk>=9
  
      We use ``os.system`` because we need to test the import of pyvista
      outside of the pytest unit test framework as pytest loads vtk.
  
      """
      exe_str = (
          "import pyvista; import sys; assert 'vtk' not in sys.modules"
      )
  
      # anything other than 0 indicates an error
      assert not os.system(
          f'{sys.executable} -c "{exe_str}"'
      ), developer_note
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_vtk_not_loaded() without return types