Relating to the "Python Tricks" you mention, remember that "is" means "these two pointers (x & y) point to the same place". You should never be to surprised wh

Relating to the "Python Tricks" you mention, remember that "is" means "these two pointers (x & y) point to the same place". You should never be to surprised when you create a bunch of new values and a language like python isn't "smart" enough to say "these are all the same value, so I'll create one of those and have x, y, etc all point to the same thing."