This is a simple python decorator to cache a functions value by input.

memoize_decorator.py

import cPickle
def memoize(original_function, function_cache={}):
    try:
        cache = function_cache[original_function]
    except KeyError:
        cache = function_cache[original_function] = {}

    def check_cache(*args, **kwargs):
        hashed_kwargs = cPickle.dumps(kwargs)
        try:
            return cache[args, hashed_kwargs]
        except KeyError:
            cache[args, hashed_kwargs] = original_function(*args, **kwargs)
        return cache[args, hashed_kwargs]

    return check_cache

# running example and performance comparison with the recursive fibonacci sequence

import timeit

@memoize
def memo_fib(n):
    if n == 0: return 0
    elif n == 1: return 1
    else: return memo_fib(n-1) + memo_fib(n-2)

def fib(n):
    if n == 0: return 0
    elif n == 1: return 1
    else: return fib(n-1) + fib(n-2)

print timeit.Timer("memo_fib(30)",
                   setup="from __main__ import memo_fib").timeit(number=1)

print timeit.Timer("fib(30)",
                   setup="from __main__ import fib").timeit(number=1)