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