code: function() {
         if ($caller !== null) {
              for(var $s = $caller.boundTo.$parent; $s !== null; $s = $s.$parent) {
                  var m = $s.prototype[$caller.methodName];
                  if (m !== undefined) {
                      return m.apply(this, arguments);
                  }
              }
          } else {
              throw new Error("$super is called outside of class context");
          }
      }
docs: TODO: not stable API, $super that doesn't throw exception is there is no super implementation