<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def to_native_units(self, motor):
 """ Return the native speed measurement required to achieve desired rotations-per-second """

        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