Remove default value from ls() function.
diff --git a/_modules/linux_netlink.py b/_modules/linux_netlink.py
index b1a3c17..52d8a1d 100644
--- a/_modules/linux_netlink.py
+++ b/_modules/linux_netlink.py
@@ -3,7 +3,7 @@
 import re
 
 
-def ls(regex=r'^[a-z0-9]+$'):
+def ls(regex):
     """
     Provide a list of network interfaces.
     """