Question about consistency in python language

[Dave Benjamin]

Mike Meyer wrote:
> Dave Benjamin <ramen at lackingtalent.com> writes:
> 
>>Python is actually quite consistent in this regard: methods that
>>modify an object in-place return None;
> 
> Um, no. list.pop comes to mind as an immediate counterexample. It may
> be the only one...

I'm sure there are counterexamples... maybe 95% is too optimistic. 
Anyone want to volunteer to compile some stats? ;)

I've never had to look up the return type of "pop" though. The only 
thing even remotely ambigious about that term (at least, if you've 
learned what a stack is) is whether it mutates the object, but I don't 
think I've ever seen a "pop" that didn't (aside from toy examples in 
formal methods / ADT related classes).

"os.system" might be a better example, since the return value could be 
one of two obvious things: the status code, or the program's output.

Dave