The current idiom
forever := make(chan bool)
gives the impression that booleans will be sent through `forever`. But
the channel never has anything sent through it; its purpose is just to
block indefinitely.
Go doesn't have any bottom type (empty type; ⊥), but it does have a unit
type, namely `struct{}`. Because not even such values will be sent, the
channel need not even exist at all, leaving no doubts as to its purpose.
