This class provides an RPC specific implementation of mx.rpc.IResponder.
It allows the creator to associate data (a token) and methods that should be
called when a request is completed.
The result method specified must have the following signature:
public function myResultFunction(result:Object, token:Object = null):void;
The fault method specified must have the following signature:
public function myFaultFunction(error:Object, token:Object = null):void;
Any other signature will result in a runtime error.