Moving over OAuth 1.0 to use Storage, and updating samples to handle token revocation.
diff --git a/samples/latitude/latitude.py b/samples/latitude/latitude.py
index 1dd1c39..c2ec635 100644
--- a/samples/latitude/latitude.py
+++ b/samples/latitude/latitude.py
@@ -28,7 +28,7 @@
 
 def main():
   credentials = Storage('latitude.dat').get()
-  if credentials is None:
+  if credentials is None or credentials.invalid == True:
     auth_discovery = build("latitude", "v1").auth_discovery()
     flow = FlowThreeLegged(auth_discovery,
                            # You MUST have a consumer key and secret tied to a