diff --git a/samples/snippets/publisher.py b/samples/snippets/publisher.py
index 4304ddf91..cf12b2626 100644
--- a/samples/snippets/publisher.py
+++ b/samples/snippets/publisher.py
@@ -88,6 +88,7 @@ def publish_messages_with_futures(project, topic_name):
 
     print('Published message IDs:')
     for future in futures:
+        # result() blocks until the message is published.
         print(future.result())