extensions/markdown-language-features/src/features/documentSymbolProvider.ts/MDDocumentSymbolProvider/provideDocumentSymbols
class MDDocumentSymbolProvider:	public async provideDocumentSymbols(document: SkinnyTextDocument): Promise<vscode.DocumentSymbol[]> {
		const toc = await new TableOfContentsProvider(this.engine, document).getToc();
		const root: MarkdownSymbol = {
			level: -Infinity,
			children: [],
			parent: undefined
		};
		this.buildTree(root, toc);
		return root.children;
	}