src/vs/workbench/contrib/markers/browser/markersTreeViewer.ts/Filter/filter
class Filter:	filter(element: MarkerElement, parentVisibility: TreeVisibility): TreeFilterResult<FilterData> {
		if (element instanceof ResourceMarkers) {
			return this.filterResourceMarkers(element);
		} else if (element instanceof Marker) {
			return this.filterMarker(element, parentVisibility);
		} else {
			return this.filterRelatedInformation(element, parentVisibility);
		}
	}