code: def ramp_down_sp(self):
          
          self._ramp_down_sp, value = self.get_attr_int(self._ramp_down_sp, 'ramp_down_sp')
          return value
docs: Writing sets the ramp down setpoint. Reading returns the current value. Units
          are in milliseconds and must be positive. When set to a non-zero value, the
          motor speed will decrease from 0 to 100% of `max_speed` over the span of this
          setpoint. The actual ramp time is the ratio of the difference between the
          `speed_sp` and the current `speed` and max_speed multiplied by `ramp_down_sp`.