extensions/markdown-language-features/src/languageFeatures/folding.ts/MdFoldingProvider/getFoldingRangeKind
class MdFoldingProvider:	private getFoldingRangeKind(listItem: Token): vscode.FoldingRangeKind | undefined {
		return listItem.type === 'html_block' && listItem.content.startsWith('<!--')
			? vscode.FoldingRangeKind.Comment
			: undefined;
	}