ledBrightness(brightness) {
		if(typeof brightness === 'undefined') {
			return this.getState('ledBrightness');
		}

		brightness = string(brightness);
		return this.changeLEDBrightness(brightness)
			.then(() => this.getState('ledBrightness'));
	}
Get or set if the LED brightness.

@param {string} brightness The LED brightness