Obtain a callback object that can be used asynchronously to re-enter the current IAsyncContextTOut, TExt with an asynchronous notification. After the notification has been invoked, eventually OnAsyncInput will be called with the given data item. This object can be cached and reused within the same IAsyncContextTOut, TExt.

AsyncCallback<TExt> GetAsyncCallback()

abstract GetAsyncCallback : unit -> AsyncCallback<'TExt>