[docs] [issue27561] Warn against subclassing builtins, and overriding their methods

Kirk Hansen added the comment: I think it could make sense at the top of the intro. It could also make sense to have it sit https://docs.python.org/2.7/library/stdtypes.html?highlight=dict#mapping-typ... and have the intro link to it, or vice-versa. Thoughts? ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue27561> _______________________________________