def trace_dispatch(self, frame, event, arg):
   if self.quitting:
      return # None
   if event == 'line':
      return self.dispatch_line(frame)
   if event == 'call':
      return self.dispatch_call(frame, arg)
   if event == 'return':
      return self.dispatch_return(frame, arg)
   if event == 'exception':
      return self.dispatch_exception(frame, arg)
   print 'bdb.Bdb.dispatch: unknown debugging event:', 'event'
   return self.trace_dispatch

Example 1: The tracefunc callback function.