code: function (params, parts) {
      var caller = parts[0];
      var fn = caller;
      for (var i = 1; i < parts.length; i++) {
        var name = parts[i];
        if (fn && fn[name] != null) {
          caller = fn;
          fn = fn[name];
        } else {
          return '';
        }
      }
      return fn.apply(caller, params || []);
    }
docs: {{y().z()}}