Globals work!!

I'm sure the road to them fully working is still perilous, but a basic example works:

```python
\#pythran export increment()
def increment():
	global a;
	a = a+1;
	print(a);

\#pythran export init()
def init():
	global a;
	a = 3;

\#pythran export test()
def test():
	init()
	increment();
```