So what is the point? I wrote this message in hope that there are more people with similar experience. My question is - how to explain to novice non-programmer users (maybe mathematically "infected") the quirks of Python sequence objects? Which methodology to use in programs so we can clearly see we work with "pointers"? Or maybe someone can propose the changes to the Language to overcome this (psychological) barrier? I feel this as a serious obstacle in using Python (my students experienced it too).
I usually draw a picture containing a few objects as boxes and a container as a separate box with arrows representing references to those boxes. I do this as early on in the tutorial as possible -- basically as soon as lists are covered. See e.g. page 16 of http://www.python.org/doc/essays/ppt/lwnyc2002/intro22.pdf (this discusses a slightly different guise of the same problem -- but it's really the same problem). --Guido van Rossum (home page: http://www.python.org/~guido/)