code: def to_native_units(self, motor):
          
          assert abs(self.degrees_per_minute) <= motor.max_dpm,\
              "invalid degrees-per-minute: {} max DPM is {}, {} was requested".format(
              motor, motor.max_dpm, self.degrees_per_minute)
          return self.degrees_per_minute/motor.max_dpm * motor.max_speed
docs: Return the native speed measurement required to achieve desired degrees-per-minute