Help- Simple recursive function to build a list

[actuary77]

I am trying to write simple recursive function to build a list:


def rec(n,alist=[]):
     _nl=alist[:]
     print n,_nl
     if n == 0:
         print n,_nl
         return _nl
     else:
         _nl=_nl+[n]
         rec(n-1,_nl)

_nl=[]
_nl=rec(4)
print _nl

### shouldn't this work?

_nl=rec(4)




The output is:
4 []
3 [4]
2 [4, 3]
1 [4, 3, 2]
0 [4, 3, 2, 1]
0 [4, 3, 2, 1]
None
None


Question:
============
Why isn't the function returning a list?
Why is function returning None?

Any guidance from one of you pro's would be greatly appreciated.

Thanks,
DKoch
actuary77 at elemental-systems.com