f-strings everywhere

docs/patterns/lazyloading.rst

@@ -93,7 +93,7 @@ write this by having a function that calls into
 name and a dot, and by wrapping `view_func` in a `LazyView` as needed.  ::
 
     def url(import_name, url_rules=[], **options):
-        view = LazyView('yourapplication.' + import_name)
+        view = LazyView(f"yourapplication.{import_name}")
         for url_rule in url_rules:
             app.add_url_rule(url_rule, view_func=view, **options)