code: def assert_equal(first, second, msg=None, extras=None):
      
      my_msg = None
      try:
          _pyunit_proxy.assertEqual(first, second)
      except AssertionError as e:
          my_msg = str(e)
          if msg:
              my_msg = "%s %s" % (my_msg, msg)
  
      # This raise statement is outside of the above except statement to prevent
      # Python3's exception message from having two tracebacks.
      if my_msg is not None:
          raise signals.TestFailure(my_msg, extras=extras)
docs: Assert the equality of objects, otherwise fail the test.
  
      Error message is "first != second" by default. Additional explanation can
      be supplied in the message.
  
      Args:
          first: The first object to compare.
          second: The second object to compare.
          msg: A string that adds additional info about the failure.
          extras: An optional field for extra information to be included in
              test result.