"Paddy" <paddy3118 at netscape.net> writes: > I would consider > t = ([1,2], [3,4]) > to be assigning a tuple with two list elements to t. > The inner lists will be mutable but I did not know you could change the > outer tuple and still have the same tuple object. Whether t is mutable is a question of definitions. Either way, you can't hash t or use it as a dictionary key.