code: def unregister(self, device, callback):
          
          if not device:
              logger.error("Received an invalid device: %r", device)
              return
  
          logger.debug("Removing subscription for {}".format(device.name))
          self._callbacks[device].remove(callback)
          self._devices[device.vera_device_id].remove(device)
docs: Remove a registered a callback.
  
          device: device that has the subscription
          callback: callback used in original registration