Update ordered_multimap.py

ordered_multimap.py

@@ -20,5 +20,8 @@ class OrderedMultiIndexMapWeakRef:
     def all_ids(self):
         return self.ids
 
+    def all_metadatas(self):
+        return [dict(d.items()) for d in index_list]
+
     def all_texts(self):
         return self.data