Consider the usage of extend:
>>> l = []
>>> l.extend(range(1, 6))
>>> print l
[1, 2, 3, 4, 5]
>>> l.extend(range(1, 6))
>>> print l
[1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
If you want to make a function (doing the same):
def fillmylist(l, n):
l.extend(range(1, n + 1))
l = []
fillmylist(l, 5)