Issue with example stringifier

The example stringifier hasn't been working for me

``` pytb
File "/Users/aaronmeurer/anaconda/lib/python3.3/bdb.py", line 49, in trace_dispatch
return self.dispatch_call(frame, arg)
File "/Users/aaronmeurer/anaconda/lib/python3.3/bdb.py", line 78, in dispatch_call
self.user_call(frame, arg)
File "/Users/aaronmeurer/anaconda/lib/python3.3/site-packages/pudb/debugger.py", line 301, in user_call
self.interaction(frame)
File "/Users/aaronmeurer/anaconda/lib/python3.3/site-packages/pudb/debugger.py", line 290, in interaction
show_exc_dialog=show_exc_dialog)
File "/Users/aaronmeurer/anaconda/lib/python3.3/site-packages/pudb/debugger.py", line 1836, in call_with_ui
return f(*args, **kwargs)
File "/Users/aaronmeurer/anaconda/lib/python3.3/site-packages/pudb/debugger.py", line 2014, in interaction
self.event_loop()
File "/Users/aaronmeurer/anaconda/lib/python3.3/site-packages/pudb/debugger.py", line 1974, in event_loop
keys = self.screen.get_input()
File "/Users/aaronmeurer/anaconda/lib/python3.3/site-packages/urwid/raw_display.py", line 292, in get_input
self._wait_for_input_ready(self._next_timeout)
File "/Users/aaronmeurer/anaconda/lib/python3.3/site-packages/urwid/raw_display.py", line 431, in _wait_for_input_ready
fd_list, [], fd_list)
File "/Users/aaronmeurer/Documents/pudb/example-stringifier.py", line 60, in
signal.signal(signal.SIGALRM, lambda s, f: timeout(s, f, time))
File "/Users/aaronmeurer/Documents/pudb/example-stringifier.py", line 50, in timeout
raise TimeOutError("Timed out after %d seconds" % time)
TimeOutError: Timed out after 0 seconds
```