diff --git a/samples/calendar_api/calendar_sample.py b/samples/calendar_api/calendar_sample.py
index 2b791430357..60c7e72ce6a 100644
--- a/samples/calendar_api/calendar_sample.py
+++ b/samples/calendar_api/calendar_sample.py
@@ -23,25 +23,27 @@
 from oauth2client import client
 from googleapiclient import sample_tools
 
+
 def main(argv):
-  # Authenticate and construct service.
-  service, flags = sample_tools.init(
-      argv, 'calendar', 'v3', __doc__, __file__,
-      scope='https://www.googleapis.com/auth/calendar.readonly')
-
-  try:
-    page_token = None
-    while True:
-      calendar_list = service.calendarList().list(pageToken=page_token).execute()
-      for calendar_list_entry in calendar_list['items']:
-        print calendar_list_entry['summary']
-      page_token = calendar_list.get('nextPageToken')
-      if not page_token:
-        break
-
-  except client.AccessTokenRefreshError:
-    print ('The credentials have been revoked or expired, please re-run'
-      'the application to re-authorize.')
+    # Authenticate and construct service.
+    service, flags = sample_tools.init(
+        argv, 'calendar', 'v3', __doc__, __file__,
+        scope='https://www.googleapis.com/auth/calendar.readonly')
+
+    try:
+        page_token = None
+        while True:
+            calendar_list = service.calendarList().list(
+                pageToken=page_token).execute()
+            for calendar_list_entry in calendar_list['items']:
+                print(calendar_list_entry['summary'])
+            page_token = calendar_list.get('nextPageToken')
+            if not page_token:
+                break
+
+    except client.AccessTokenRefreshError:
+        print('The credentials have been revoked or expired, please re-run'
+              'the application to re-authorize.')
 
 if __name__ == '__main__':
-  main(sys.argv)
+    main(sys.argv)