Rotating lists?

[Ivan Voras]

I need to transform this:

[1,2,3]

into this:

[2,3,1]

(a left-rotation. Actually, any rotation will do).

I tried:

a = a[1:] + a[0]

which doesn't work because there's no __add__ between a list and 
integer, and:

a = a[1:].append(a[0])

but it doesn't work, since append returns None :( Right now, I'm doing 
it with a temporary variable and it looks ugly - is there an elegant way 
of doing it?