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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 save_token(self, access_token):
 """ Stores the access token and additional data in memcache. See :class:`oauth2.store.AccessTokenStore`. """

        key = self._generate_cache_key(access_token.token)
        self.mc.set(key, access_token.__dict__)

        unique_token_key = self._unique_token_key(access_token.client_id,
                                                  access_token.grant_type,
                                                  access_token.user_id)
        self.mc.set(self._generate_cache_key(unique_token_key),
                    access_token.__dict__)

        if access_token.refresh_token is not None:
            rft_key = self._generate_cache_key(access_token.refresh_token)
            self.mc.set(rft_key, access_token.__dict__)