code: def add_event_detect(self, pin, edge, callback=None, bouncetime=-1):
          
          kwargs = {}
          if callback:
              kwargs['callback']=callback
          if bouncetime > 0:
              kwargs['bouncetime']=bouncetime
          self.rpi_gpio.add_event_detect(pin, self._edge_mapping[edge], **kwargs)
docs: Enable edge detection events for a particular GPIO channel.  Pin 
          should be type IN.  Edge must be RISING, FALLING or BOTH.  Callback is a
          function for the event.  Bouncetime is switch bounce timeout in ms for
          callback