def count(self, *args, **kw):
        """ Counts whether the computed key value is already present
           in the memoization dictionary (a hit) or not (a miss).
        """
        obj = args[0]
        try:
            memo_dict = obj._memo[self.method_name]
        except KeyError:
            self.miss = self.miss + 1
        else:
            key = self.keymaker(*args, **kw)
            if key in memo_dict:
                self.hit = self.hit + 1
            else:
                self.miss = self.miss + 1
Counts whether the computed key value is already present
           in the memoization dictionary (a hit) or not (a miss).