gistfile1.py

def memoize(f):
    def mem(x):
        if x not in cache:
            cache[x] = f(x)
        return cache[x]
    cache = {}
    return mem

#@memoize
def fib(n=1):
    if n <= 1:
        return 1
    else:
        return fib(n-1) + fib(n-2)

fib = memoize(fib)