why does this unpacking work

[John Salerno]

Carsten Haese wrote:

> You seem to have difficulty distinguishing the concept of looping over a
> tuple from the concept of unpacking a tuple. 

I think you're right. It's starting to make more sense now. I think when 
I saw:

for x,y in t

I was expecting 't' to be a two-tuple for it to work. Maybe writing it as:

for (x,y) in t

sort of helps to show that '(x,y)' is equivalent to one object in 't'. 
That makes it look a little more cohesive in my mind, I guess, or helps 
me to see it map out against 't' better.