python: conditional context and ExitStack (intermediate) anthony explains #189

Whoa. I can use this to also open multiple files to write into. Brilliant. Thanks Anthony.

If i leave a file open, does it automatically get freed once my python process ends, at least on linux?

The third option is very neat. I hope I'll remember it when I'll need it.
So far I've been "writing" to multiple outputs only when using logging with multiple handlers.