On Fri, Apr 01 2011, Baishampayan Ghose wrote: [...] >>>> foo = (1, [2, 3, 4]) >>>> foo[1].append(5) >>>> foo > (1, [2, 3, 4, 5]) >>>> foo[1].append(6) >>>> foo > (1, [2, 3, 4, 5, 6]) This is an inplace modification. Does the other one "change" the list in some sense that the tuple gets annoyed? [...] --