:art: Add ** operator.

diff --git a/plug b/plug
index ef3f1e49b8d16afe29090ada2a933e5d994f521c..9da3f7375460424e60302be23a66b84860833a92 160000 (submodule)
--- a/plug
+++ b/plug
@@ -1 +1 @@
-Subproject commit ef3f1e49b8d16afe29090ada2a933e5d994f521c
+Subproject commit 9da3f7375460424e60302be23a66b84860833a92