setAmbientPower(power) {
		return this.call.send('enable_amb', [ power ? 'on' : 'off' ])
			.then(MiioApi.checkOk);
	}
Set the current eyeCare mode

	changeMode(mode) {

		switch (mode) {
			case 'study':
				mode = 1;
				break;
			case 'reading':
				mode = 2;
				break;
			case 'phone':
				mode = 3;
				break;
			default:
				return Promise.reject(new Error('Invalid EyeCare Mode: ' + mode));
		}
		return this.call('set_user_scene', [mode], {
			refresh: true
		});
	}