code: func (g *Driver) SetPWMDuty(port Grove, duty uint16) (err error) {
  	if duty < 0 {
  		duty = 0
  	}
  	if duty > 100 {
  		duty = 100
  	}
  	duty = duty * 10
  	return g.writeBytes([]byte{
  		goPiGo3Address,
  		SET_GROVE_PWM_DUTY,
  		byte(port),
  		byte((duty >> 8) & 0xFF),
  		byte(duty & 0xFF),
  	})
  }
docs: // SetPWMDuty sets the pwm duty cycle for the given pin/port.