--- a/doc/tutorials/advanced/part04_ui-base.rst	Tue Feb 26 16:25:27 2019 +0100
+++ b/doc/tutorials/advanced/part04_ui-base.rst	Tue Feb 26 16:25:44 2019 +0100
@@ -183,10 +183,13 @@
             rql = self.entity.cw_related_rql(self.tree_relation,
                                              self.parent_role, ('File',))
             rset = self._cw.execute(rql, {'x': self.entity.eid})
+
             if entities:
                 return list(rset.entities())
+
             return rset
 
+
     def registration_callback(vreg):
         vreg.register_and_replace(FolderITreeAdapter, folder.FolderITreeAdapter)