cyclic data structures

[John Salerno]

Carsten Haese wrote:

> L is [1,2] before the append. After the append, L is [1,2,L], which is
> [1,2,[1,2,L]], which is [1,2,[1,2,[1,2,L]]] etc into infinity. L
> literally contains itself after the append.

Ah, this perfectly explains it now! I guess I was dancing around this 
fact, but now that you've typed it out, I see that L actually changed in 
place!

Thanks guys!