code: def test_theme_use(self):
      self.assertRaises(
          tkinter.TclError, self.style.theme_use, "nonexistingname"
      )
  
      curr_theme = self.style.theme_use()
      new_theme = None
      for theme in self.style.theme_names():
          if theme != curr_theme:
              new_theme = theme
              self.style.theme_use(theme)
              break
      else:
          # just one theme available, can't go on with tests
          return
  
      self.assertFalse(curr_theme == new_theme)
      self.assertFalse(new_theme != self.style.theme_use())
  
      self.style.theme_use(curr_theme)
  
file_path: catboost/contrib/tools/python/src/Lib/lib-tk/test/test_ttk/test_style.py
imports: import unittest
  import Tkinter
  import ttk
  from test.test_support import requires, run_unittest
  from test_ttk.support import AbstractTkTest
label_desc: Use image node_id 6 for calling the StyleTest obj's underlying member method code with example usage: obj.test_theme_use() without return types