get() {
        let permission;

        /* Safari 6+, Chrome 23+ */
        if (this._win.Notification && this._win.Notification.permission)
            permission = this._win.Notification.permission;
        else if (
            this._win.webkitNotifications &&
            this._win.webkitNotifications.checkPermission
        )
            /* Legacy webkit browsers */
            permission = this._permissions[
                this._win.webkitNotifications.checkPermission()
            ];
        else if (navigator.mozNotification)
            /* Firefox Mobile */
            permission = this.GRANTED;
        else if (this._win.external && this._win.external.msIsSiteMode)
            /* IE9+ */
            permission = this._win.external.msIsSiteMode()
                ? this.GRANTED
                : this.DEFAULT;
        else permission = this.GRANTED;

        return permission;
    }
Gets the permission level
@return {Permission} The permission level