code: def cleanup(self, timeout):
          '''
          Removes all sessions older than ``timeout`` seconds.
          Called automatically on every session access.
          '''
          cutoff = time() - timeout
          self.collection.remove({_atime: {'$lt': cutoff}}f cleanup(self, timeout):
          '''
          Removes all sessions older than ``timeout`` seconds.
          Called automatically on every session access.
          '''
          cutoff = time() - timeout
          self.collection.remove({_atime: {'$lt': cutoff}})
docs: Removes all sessions older than ``timeout`` seconds.
          Called automatically on every session access.