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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 memo(f):
 """ A decorator function you should apply to ``copy`` """

        def inner(self, memo=None, **kwargs):
            if memo is None:
                memo = {}
            if id(self) in memo:
                return memo[id(self)]
            else:
                c = f(self, memo, **kwargs)
                memo[id(self)] = c
                return c
        return inner