I am trying to use following handler but unable to figured out how? could you please give me some example for specifically this handler.

function callback_after_execute_handler(callback, output, extraData)

Actually in this callback panel, on the click of a button, I am executing some server side function, after updating different fields on the callback panel it returns either true or false. Fields updated correctly, but I also want this true/false value on the client side, so i can invoke appropriate javascript. I think this function can help me doing that. but How can i set and get that parameter.

Thanks