code: def testUnsetVarException(self):
      tcl = self.interp
      self.assertRaises(TclError, tcl.unsetvar, "a")
  
imports: import unittest
  import subprocess
  import sys
  import os
  from test import support
  from test.support import import_helper
  from test.support import os_helper
  import tkinter
  from tkinter import Tcl
  from _tkinter import TclError
label_desc: Use image node_id 18 for calling the TclTest obj's underlying member method code with example usage: obj.testUnsetVarException() without return types