How to use the @hpcc-js/leaflet-shim.CRS.EPSG3857 function in @hpcc-js/leaflet-shim

init(): Promise;
    hasBounds(): boolean;
    getBounds(): LatLngBounds;

    layerEnter(map: Map);
    layerUpdate(map: Map);
    layerExit(map: Map);

    zoomEnd(e);
    moveEnd(e);
    viewReset(e);
}

export class TileLayer extends Widget implements ILayer {
    private _layer = new FeatureGroup();
    protected _crs: any = CRS.EPSG3857;

    constructor(cluster = false) {
        super();
        (this._layer as any).__hpcc_layer = this;
    }

    crs() {
        return this._crs;
    }

    attribution(): string {
        return "";
    }

    clear() {
        this._layer.clearLayers();