docs: def time_left(self, key):
          """
          Gets the amount of time an item has left in the cache (in seconds), before it is evicted.
  
          :param key: Key to check time for.
          :returns: int
          """
          self._evict_old()
  
          if key not in self._store:
              raise KeyError("key {0!r} does not exist in cache".format(key))
  
          return self.timeout - (time.time() - self._store[key][1])