appended new line to Args section

lib/old_sets.bzl

diff --git a/lib/old_sets.bzl b/lib/old_sets.bzl
index 8cb6862..2ac6c6b 100644
--- a/lib/old_sets.bzl
+++ b/lib/old_sets.bzl
@@ -51,6 +51,7 @@
 
     Args:
       val: The value to be optionally converted and returned.
+
     Returns:
       The converted value.
     """