Can someone explain to me what the following are and how it is supposed to be used:

1. Global Constant
2. Precedence of Operators
3. __builtin__
4. main
5. raw_input

Also, how come whenever I type in

>>>def f():
return 2, 34.7, "hi"

I get this instead:

(2, 34.7000000003, 'hi')

Notice how the number has changed.