I like the proposal. I agree that filter(None, ...) is not discoverable (and has its own magic).

So the proposal would be: prune=False -> empty strings stay, prune=True, empty strings are dropped, prune=None (default) use True if sep is None, False otherwise. Right?

Some end cases:

- ''.split(None, prune=True) -> ['']
- 'x  x'.split(None, prune=True) -> ['x', '', 'x']

Right?

While we're here I wish there was a specific argument we could translate .split(None) into, e.g. x.split() == x.split((' ', '\t', '\n', '\r', '\f')) # or whatever set of strings