anchor.diff:    /**
      * Create a new extension loader for the given pluggable.
      */
  -  Extensible([this.pluggable]);
  +  Extensible([this._pluggable]);
  +
  +  /**
  +   * The argument passed during plugin setup.
  +   *
  +   * Either passed on instantiation, or will be this,
  +   */
  +  dynamic get pluggable => _pluggable != null ? _pluggable : this;
   
     /**
      * Load an extension.
      */
  -  Future extend(Extension plugin) {
  -    Future f = plugin(pluggable != null ? pluggable : this);
  -    if (f != null) {
  -      waitingFor.add(f);
  +  dynamic extend(Extension plugin) {
  +    var result = plugin(pluggable);
  +    if (result is Future) {
  +      waitingFor.add(result);
       }
  -    return f;
  +    return result;
     }
   
     /**
  
positive.code:   /**
     * The instance being extended, will be passed to all extensions.
     */
    final dynamic pluggable;
  
    /**
     * The list of futures that this loader will wait on.
  
negative.code: /**
   * The function type of a plugin.
   */
  typedef dynamic Extension(dynamic pluggable);
  
  
  /**
  