code: func changePinMode(a *Adaptor, pin, mode string) (err error) {
  	_, err = a.writeFile(
  		"/sys/kernel/debug/gpio_debug/gpio"+pin+"/current_pinmux",
  		[]byte("mode"+mode),
  	)
  	return
  }
docs: // changePinMode writes pin mode to current_pinmux file