request(onGranted: () => void, onDenied: () => void) {
        return arguments.length > 0
            ? this._requestWithCallback(...arguments)
            : this._requestAsPromise();
    }
Requests permission for desktop notifications
@param {Function} onGranted - Function to execute once permission is granted
@param {Function} onDenied - Function to execute once permission is denied
@return {void, Promise}