'Return the device state attributes.'

@property
def device_state_attributes(self):

    data = {}
    if (self.signal is not None):
        data[ATTR_SIGNAL_STRENGTH] = self.signal
    if (self.dist is not None):
        data[ATTR_DISTANCE_SENSOR] = self.dist
    if (self._state is not None):
        data[ATTR_DOOR_STATE] = self._state
    return data
