#!/usr/bin/env python
# -*- coding:utf-8 -*-

def split_list(alist, n, newlist):
    if len(alist) >= n:
        newlist.append(alist[:n])
        return split_list(alist[n:len(alist)], n, newlist)
    else:
        newlist.append(alist)
        return newlist

alist = range(21)

print split_list(alist, 5, [])