def add_event_callback(self, pin, callback, bouncetime=-<NUM_LIT:1>):
kwargs = {}<EOL>if bouncetime > <NUM_LIT:0>:<EOL><INDENT>kwargs['<STR_LIT>']=bouncetime<EOL><DEDENT>self.bbio_gpio.add_event_callback(pin, callback, **kwargs)<EOL>
Add a callback for an event already defined using add_event_detect().
        Pin should be type IN.  Bouncetime is switch bounce timeout in ms for 
        callback