Question about None

Terry Reedy tjreedy at
Sat Jun 13 18:27:45 CEST 2009

Steven D'Aprano wrote:
[ snip excellent discussion of proper use of assert]

> The third bug (the nitpick) is a bug in the API: you name the argument "nxt"
> with no e, but in the error message, you call it "next" with an e. The fact
> that any intelligent person should be able to guess what parameter the
> error is referring to doesn't make it less wrong.
> So, fixing the three issues:
> def setNext(next):
>     if not (next is None or isinstance(next, Node)):
>         raise ValueError("next must be a Node")
> = next

[counternit] Of course, next() is a builtin function and some consider 
reusing builtin names as bare names (versus attribute names) a bad 
habit.  I think the OP had a good idea in using a variation, but should 
have been consistent.

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