No trees in the stdlib?

[Stefan Behnel]

Hallvard B Furuseth wrote:
> Stefan Behnel writes:
>> João Valverde wrote:
>>> Besides some interface glitches, like returning None
>>> on delete if I recall correctly.
>> That's actually not /that/ uncommon. Operations that change an object are
>> not (side-effect free) functions, so it's just purity if they do not have a
>> return value.
> 
> It's purity that they don't return the modified tree/dict/whatever.
> They can still return the deleted element and remain pure.

Fair enough.

Stefan