src/vs/workbench/contrib/callHierarchy/browser/callHierarchyTree.ts/CallRenderer/renderTemplate
class CallRenderer:	renderTemplate(container: HTMLElement): CallRenderingTemplate {
		container.classList.add('callhierarchy-element');
		const icon = document.createElement('div');
		container.appendChild(icon);
		const label = new IconLabel(container, { supportHighlights: true });
		return new CallRenderingTemplate(icon, label);
	}