code: function() {
    var res = this.match(reLinkDestinationBraces);
    if (res) {  // chop off surrounding <..>:
      return unescape(res.substr(1, res.length - 2));
    } else {
      res = this.match(reLinkDestination);
      if (res !== null) {
        return unescape(res);
      } else {
        return null;
      }
    }
  }
docs: Attempt to parse link destination, returning the string or null if no match.