Clarify comment.

clokep · web-flow · commit 28d4b8adc72e · 2020-08-24T12:30:45.000-04:00
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py
@@ -714,7 +714,7 @@ def get_auth_chain_difference(
         chain.
 
         Returns:
-            Set of event IDs.
+            An awaitable that resolves to a set of event IDs.
         """
 
         return self.store.get_auth_chain_difference(state_sets)
