[docs] [issue14097] Improve the "introduction" page of the tutorial

Raymond Hettinger added the comment: Please add the "x = y = z = 0" example back. It doesn't improve the tutorial to dumb it down or to leave out basic knowledge. You may not like the feature but it is a long standing part of the core language. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue14097> _______________________________________