beginTedious k starts a tedious process and registers it in
_progressData with the key k. A tedious process is one for which we
want a progress indicator.
Wouldn't it be safer if it had type String -> IO
ProgressDataKey, so that we can ensure there is no collision?
What happens if you call beginTedious twice with the same string, without
calling endTedious in the meantime?
|endTedious k unregisters the tedious process with key k, printing Done if such
a tedious process exists.
|Produced by Haddock version 2.4.2|