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