lst = [3, 6, 2, 1, 0] lst2 = [1, 2] print map(bool, lst) def outer(): def inner(item): return 2 * item print map(inner, lst) outer() print map(None, lst, lst2) #filter with builtin functions print filter(bool, [0,1,"",False,42,[1]]) #reduce with global variables adder = 100 def add(x, y): return x + y + adder print reduce(add, [3, -7, 1], 100)