2Qs

[JW]

> > 2nd question:
> [snip]
> > if x>10 and y>10 and z>10 and summ(tritup(x,y,z)): print "OK"
>
> Others have already suggested you use the built-in sum() function.
>
> I'll suggest you don't need it at all, because it is redundant.
>
> If the sum is zero, either all three values are zero or at least one of
> the values is negative. In either case the first test will fail.
>
> There are no circumstances where each of x, y and z are greater than 10
> but the sum is zero; nor are there any circumstances where the sum is
> zero but x, y and z are still all greater than 10.

Unless, of course, the function tritup returns negative values.  My
guess is that the "> 10" tests are protecting the tritup function, and
possibly should be moved there.  Without the details of the function, I
can't tell, but it may be incorrect to remove those tests.

Which brings us to the other bit of advice - unit tests protect you
from yourself and from those who optimize too quickly.