fix formatting (#115)

lib/src/tree.dart

diff --git a/lib/src/tree.dart b/lib/src/tree.dart
index b567f3c..83e8b09 100644
--- a/lib/src/tree.dart
+++ b/lib/src/tree.dart
@@ -212,7 +212,9 @@
 
   String get namespace => _namespace is Wildcard
       ? '*'
-      : _namespace == null ? '' : _namespace.name as String;
+      : _namespace == null
+          ? ''
+          : _namespace.name as String;
 
   bool get isNamespaceWildcard => _namespace is Wildcard;