src/vs/base/browser/ui/tree/abstractTree.ts/TreeRenderer/renderTemplate
class TreeRenderer:	renderTemplate(container: HTMLElement): ITreeListTemplateData<TTemplateData> {
		const el = append(container, $('.monaco-tl-row'));
		const indent = append(el, $('.monaco-tl-indent'));
		const twistie = append(el, $('.monaco-tl-twistie'));
		const contents = append(el, $('.monaco-tl-contents'));
		const templateData = this.renderer.renderTemplate(contents);

		return { container, indent, twistie, indentGuidesDisposable: Disposable.None, templateData };
	}