code: func (s *StepperDriver) SetSpeed(rpm uint) error {
  	if rpm <= 0 {
  		return errors.New("RPM cannot be a zero or negative value")
  	}
  
  	m := s.GetMaxSpeed()
  	if rpm > m {
  		rpm = m
  	}
  
  	s.speed = rpm
  	return nil
  }
docs: // SetSpeed sets the rpm