Remove innecesary conditional

Author: Hugo Osvaldo Barrera

todoman/cli.py

@@ -36,9 +36,8 @@ def wrapper(*a, **kw):
 with_id_arg = click.argument('id', type=click.IntRange(min=TODO_ID_MIN))
 
 
-def _validate_lists_param(ctx, param=None, lists=None):
-    if lists:
-        return [_validate_list_param(ctx, name=l) for l in lists]
+def _validate_lists_param(ctx, param=None, lists=[]):
+    return [_validate_list_param(ctx, name=l) for l in lists]
 
 
 def _validate_list_param(ctx, param=None, name=None):