How to use the recyclerlistview/web.DataProvider function in recyclerlistview

constructor(args) {
        super(args);

        let width = window.innerWidth;

        //Create the data provider and provide method which takes in two rows of data and return if those two are different or not.
        let dataProvider = new DataProvider((r1, r2) => {
            return r1 !== r2;
        });

        //Create the layout provider
        //First method: Given an index return the type of item e.g ListItemType1, ListItemType2 in case you have variety of items in your list/grid
        //Second: Given a type and object set the height and width for that type on given object
        //If you need data based check you can access your data provider here
        //You'll need data in most cases, we don't provide it by default to enable things like data virtualization in the future
        //NOTE: For complex lists LayoutProvider will also be complex it would then make sense to move it to a different file
        this._layoutProvider = new LayoutProvider(
            index => {
                if (index % 3 === 0) {
                    return ViewTypes.FULL;
                } else if (index % 3 === 1) {
                    return ViewTypes.HALF_LEFT;
                } else {