code: function() {
    var fn = this.__superFunction;
    var self = this;
    var bound = function _super() {
      if (this && this !== self) {
        throw new Error('_super cannot change `this` use _super.unbound');
      }
      return fn && fn.apply(self, arguments);
    };
    return _.extend(bound, { unbound: fn });
  }
docs: Call the superclass's version of the current method. This method is
  available for both instance and static methods. It is pre-bound to the
  current instance, so bind/call/apply cannot be used to set the value of
  `this`.
  
  @name Class._super
  @method
  @public