cyclic data structures

[Duncan Booth]

John Salerno wrote:

> L.append(L) basically creates this, I think:
> 
> [1, 2, L]

Correct.
> 
> Now, assuming that's correct, and since L points to the list [1, 2],

wrong. You just said it yourself: L is now the list [1, 2, L]

> why 
> can't '[1, 2]' be substituted for the 'L' and then the list is closed?
> 
The append method modifies the list in place. The list which contained 1,2 
now has a third element which is a reference to itself.