+class BookProxy(models.Model):
+    def __init__(self, book, key):
+        self.book = book
+        self.key = key
+
+    def __getattr__(self, item):
+        if item not in ('book', 'key'):
+            return self.book.__getattribute__(item)
+        else:
+            return self.__getattribute__(item)
+
+
+class QuerySetProxy(models.QuerySet):
+    def __init__(self, l):
+        self.list = l
+
+    def __iter__(self):
+        return iter(self.list)
+
+