class Memoize:
    """
    Example usage:
    >>> @Memoize
    ... def fib(n):
    ...     if n <= 1:
    ...         return n
    ...     else:
    ...         return fib(n - 1) + fib(n - 2)
    >>> fib(300)
    222232244629420445529739893461909967206666939096499764990979600L
    """
    def __init__(self, f):
        self.f = f
        self.memo = {}

    def __call__(self, *args):
        if args in self.memo:
            return self.memo[args]
        else:
            result = self.f(*args)
            self.memo[args] = result
            return result