docs: def add(self, key, val, minutes):
          """
          Store an item in the cache if it does not exist.
  
          :param key: The cache key
          :type key: str
  
          :param val: The cache value
          :type val: mixed
  
          :param minutes: The lifetime in minutes of the cached value
          :type minutes: int|datetime
  
          :rtype: bool
          """
          if not self.has(key):
              self.put(key, val, minutes)
  
              return True
  
          return False