[utils] Split out traversal.py dummy and traversal tests

youtube_dl/traversal.py

@@ -0,0 +1,10 @@
+# coding: utf-8
+
+# TODO: move these utils.fns here and move import to utils
+# flake8: noqa
+from .utils import (
+    dict_get,
+    get_first,
+    T,
+    traverse_obj,
+)