Now I can see it allows you do "discard" all the pending reads from the input channel (and avoid writing to a possibly-closed 'out' channel), but wouldn't it be better to break the loop in this case for an immediate exit?
i.e. go for 'interrupt' semantics, rather than 'drain'?
for n := range in {
select {
case out <- n * n:
case <-done:
return
}
}
If `break` is used, for loop is terminated once it's "done", hence nothing would be reading from channel `c`. The previous station in the pipeline would then block at sending operation.