def get(self, key):
        """Get an item from the cache
           Args:
               key: item key
           Returns:
               the value of the item or None if the item isn't in the cache
        """
        data = self._store.get(key)
        if not data:
            return None
        value, expire = data
        if expire and time.time() > expire:
            del self._store[key]
            return None
        return value