Cache._items is a {id: [item, timeout]} dict, not {id: item}

src/Cache.py

@@ -31,7 +31,7 @@ class Cache(object):
             if expiration and expiration <= now:
                 expired.append(id)
         for id in expired:
-            item = self._items[id]
+            item, expiration = self._items[id]
             del self._items[id]
             del self._item_to_id[item]