extensions/markdown-language-features/src/markdownEngine.ts/MarkdownItEngine/addNamedHeaders
class MarkdownItEngine:	private addNamedHeaders(md: MarkdownIt): void {
		const original = md.renderer.rules.heading_open;
		md.renderer.rules.heading_open = (tokens: Token[], idx: number, options, env, self) => {
			const title = tokens[idx + 1].children!.reduce<string>((acc, t) => acc + t.content, '');
			let slug = this.slugifier.fromHeading(title);

			if (this._slugCount.has(slug.value)) {
				const count = this._slugCount.get(slug.value)!;
				this._slugCount.set(slug.value, count + 1);
				slug = this.slugifier.fromHeading(slug.value + '-' + (count + 1));
			} else {
				this._slugCount.set(slug.value, 0);
			}

			tokens[idx].attrSet('id', slug.value);

			if (original) {
				return original(tokens, idx, options, env, self);
			} else {
				return self.renderToken(tokens, idx, options);
			}
		};
	}