code: def get(self, key):
          
          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
docs: 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