303 // Stanzas from the remote go up through a stack of filters to the

   304 // app. This function manages the filters.

   305 func filterTop(filterOut <-chan <-chan Stanza, filterIn chan<- <-chan Stanza,

   306 	topFilter <-chan Stanza, app chan<- Stanza) {

   307 	defer close(app)

   308 Loop:

   309 	for {

   310 		select {

   311 		case newFilterOut := <-filterOut:

   312 			if newFilterOut == nil {

   313 				Warn.Log("Received nil filter")

   314 				filterIn <- nil

   315 				continue

   316 			}

   317 			filterIn <- topFilter

   318 			topFilter = newFilterOut

   319 

   320 		case data, ok := <-topFilter:

   321 			if !ok {

   322 				break Loop

   323 			}

   324 			app <- data

   325 		}

   326 	}

   327 }

   328 

   329 func filterBottom(from <-chan Stanza, to chan<- Stanza) {

   330 	defer close(to)

   331 	for data := range from {

   332 		to <- data

   333 	}

   334 }

   335