'Add a new item, or reset the expiry time of an existing item.'

def add(self, item, now=None):

    now = (now or time.time())
    if (item in self._data):
        self.discard(item)
    entry = (now, item)
    self._data[item] = entry
    heappush(self._heap, entry)
    if (self.maxlen and (len(self._data) >= self.maxlen)):
        self.purge()
