The worst thing about CoffeeScript is that you are used to having scoping work a different way?

Let's extend your example:

    >>> a = 1
    >>> def foo():
          print a
    >>> foo()
    1

So Python does take from the outer scope?

    >>> a = 1
    >>> def foo():
          a = 2
          print a
    >>> foo()
    2

Or not?

    >>> a = 1
    >>> def foo():
          print a
          a = 2
    >>> foo()
    UnboundLocalError: local variable 'a' referenced before assignment

Or it just doesn't work at all?

Next time, pick a better example. The answer to "What does Python do with a variable from outside a function's scope?" is "It depends."

At least CoffeeScript is consistent.