R. David Murray added the comment: What is actually happening is that the *contents* of the list are copied, but the list itself is not. This is a consequence of the definition in terms of +. So, yes, that is a shallow copy, but not quite in the sense that mylist.copy() is a shallow copy, since the references to the contents of s get appended to the list being constructed by *, not a new list that is a "copy" of s. You are correct that "s is only referenced" is not really accurate. But how about "Note that the contents of the *s* object are not copied, they are referenced multiple times". I think that highlights the source of the confusion: that the *contents* are not copied. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue23406> _______________________________________