code: func (p *PWMPin) InvertPolarity(invert bool) (err error) {
  	if !p.enabled {
  		polarity := "normal"
  		if invert {
  			polarity = "inverted"
  		}
  		_, err = p.write(p.pwmPolarityPath(), []byte(polarity))
  	} else {
  		err = fmt.Errorf("Cannot set PWM polarity when enabled")
  	}
  	return
  }
docs: // InvertPolarity writes value to pwm polarity path