>> def f(x): >> x = x + (1,2,3) >> print x >A vast improvement: clear, unambiguous, and correct. I can safely pass a >list as an argument and not have it modified behind my back. Eek. I finally got what everyone is talking about. x += (1,2,3) ... is not the same as... x=x+(1,2,3) That's just plain wrong. C//