tracks/ocaml/exercises/zipper/tree.ml in trackler-2.1.0.21 vs tracks/ocaml/exercises/zipper/tree.ml in trackler-2.1.0.22

@@ -1,5 +1,5 @@
-open Core.Std
+open Core
 
 type 'a t = { value : 'a; left : 'a t option; right : 'a t option }
   [@@deriving sexp]
 
 let rec equal veq a b =