Adding optional 'explicit' declaration?

[Clarence Gardner]

>>>> The transparent creation of variables in Python is really nice, but
>>>> there are times when it become a bug source, essentially because of
>>>> misstyping of variable names.
>>>
>>>Does anyone have any numbers on this? People make this claim all the
>>>time, but in practice my typos are always caught at compile time or
>>>immediate testing already. I believe bugs like this are really rare.

But even if typos (which cause NameErrors particularly) are found the
first time you run the program, which is often the case, if the program runs
for an hour before hitting the error (which happened to me the other day),
that's still an annoyance.