code: function(walk) {
      if (!walk.at("<")) return false;
      if (this.tryHtmlTag(walk)) return true;
      if (this.tryHtmlComment(walk)) return true;
      // Not HTML tag -- escaping <
      this.out.push("&lt;");
      walk.skip();
      return true;
    }
docs: /* The `<` char should be escaped, unless it is a part of HTML tag.