From d61a04583eda3ba4deea4b82b93e61903919e1a8 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 1 Feb 2017 17:35:23 +0000
Subject: [PATCH] Comment

---
 synapse/storage/stream.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index cdc183889..3765d0095 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -245,6 +245,9 @@ class StreamStore(SQLBaseStore):
         defer.returnValue(results)
 
     def get_rooms_that_changed(self, room_ids, from_key):
+        """Given a list of rooms and a token, return rooms where there may have
+        been changes.
+        """
         from_key = RoomStreamToken.parse_stream_token(from_key).stream
         return set(
             room_id for room_id in room_ids