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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 cached(func):
 """ A decorator function to cache values. It uses the decorated function's arguments as the keys to determine if the function has been called previously. """

    cache = {}

    @f.wraps(func)
    def wrapper(*args, **kwargs):
        key = func.__name__ + str(sorted(args)) + str(sorted(kwargs.items()))
        if key not in cache:
            cache[key] = func(*args, **kwargs)
        return cache[key]
    return wrapper