src/vs/workbench/contrib/callHierarchy/browser/callHierarchyTree.ts/Call/compare
class Call:	static compare(a: Call, b: Call): number {
		let res = compare(a.item.uri.toString(), b.item.uri.toString());
		if (res === 0) {
			res = Range.compareRangesUsingStarts(a.item.range, b.item.range);
		}
		return res;
	}