code: def testInstallHandler(self):
      default_handler = signal.getsignal(signal.SIGINT)
      unittest.installHandler()
      self.assertNotEqual(
          signal.getsignal(signal.SIGINT), default_handler
      )
  
      try:
          pid = os.getpid()
          os.kill(pid, signal.SIGINT)
      except KeyboardInterrupt:
          self.fail("KeyboardInterrupt not handled")
  
      self.assertTrue(unittest.signals._interrupt_handler.called)
  
imports: import gc
  import os
  import sys
  import signal
  import weakref
  from cStringIO import StringIO
  import unittest
label_desc: Use image node_id 3 for calling the TestBreak obj's underlying member method code with example usage: obj.testInstallHandler() without return types