diff --git a/flask/helpers.py b/flask/helpers.py
index 7423aca8..5ae977cb 100644
--- a/flask/helpers.py
+++ b/flask/helpers.py
@@ -195,7 +195,6 @@ def url_for(*args, **kwargs):
     wrapper based on https://github.com/miguelgrinberg/flack/blob/master/flack/utils.py
     that also covers the case where application context exists with SERVER_NAME defined.
     """
-
     reqctx = _request_ctx_stack.top
     appctx = _app_ctx_stack.top
     if reqctx is None and (appctx is None or appctx.url_adapter is None):
@@ -317,7 +316,6 @@ def _url_for(endpoint, **values):
                                'adapter for request independent URL generation. '
                                'You might be able to fix this by setting '
                                'the SERVER_NAME config variable.')
-
         external = values.pop('_external', True)
 
     anchor = values.pop('_anchor', None)