extensions/markdown-language-features/src/tableOfContentsProvider.ts/TableOfContentsProvider/lookup
class TableOfContentsProvider:	public async lookup(fragment: string): Promise<TocEntry | undefined> {
		const toc = await this.getToc();
		const slug = githubSlugifier.fromHeading(fragment);
		return toc.find(entry => entry.slug.equals(slug));
	}