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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def memoize(fn=None):
 """Caches the result of the provided function."""

    cache = { }
    arg_hash_fn = fn_arg_hash_function(fn)

    def decorated(*args, **kwargs):
        try:
            hash_ = arg_hash_fn(*args, **kwargs)
        except TypeError:
            return fn(*args, **kwargs)

        try:
            return cache[hash_]
        except KeyError:
            return_val = fn(*args, **kwargs)
            cache[hash_] = return_val
            return return_val
    _functools.update_wrapper(decorated, fn)

    return decorated