changeMode(mode) {
		return this.call('set_mode', [ mode ], {
			refresh: [ 'power', 'mode' ],
			refreshDelay: 200
		})
			.then(MiioApi.checkOk)
			.catch(err => {
				throw err.code === -5001 ? new Error('Mode `' + mode + '` not supported') : err;
			});
	}
Perform a mode change as requested by `mode(string)` or
`setMode(string)`.