Simplify example code

As has_role returns a boolean anyway, there is no need for another if-statement.

examples/auth/app.py

@@ -54,15 +54,10 @@ security = Security(app, user_datastore)
 
 # Create customized model view class
 class MyModelView(sqla.ModelView):
-
     def is_accessible(self):
         if not current_user.is_active or not current_user.is_authenticated:
             return False
-
-        if current_user.has_role('superuser'):
-            return True
-
-        return False
+        return current_user.has_role('superuser')
 
     def _handle_view(self, name, **kwargs):
         """