diff --git a/src/lib_utils/PP.ml b/src/lib_utils/PP.ml
index 1665d4a57..a32854c6f 100644
--- a/src/lib_utils/PP.ml
+++ b/src/lib_utils/PP.ml
@@ -18,6 +18,14 @@ let ne_list_sep value separator ppf (hd, tl) =
 let prepend s f ppf a =
   fprintf ppf "%s%a" s f a
 
+let option = fun f ppf opt ->
+  match opt with
+  | Some x -> fprintf ppf "Some(%a)" f x
+  | None -> fprintf ppf "None"
+
+let map = fun f pp ppf x ->
+  pp ppf (f x)
+
 let pair_sep value sep ppf (a, b) = fprintf ppf "%a %s %a" value a sep value b
 let smap_sep value sep ppf m =
   let module SMap = X_map.String in
diff --git a/src/lib_utils/dictionary.ml b/src/lib_utils/dictionary.ml
index 76fc8cb14..130c01af8 100644
--- a/src/lib_utils/dictionary.ml
+++ b/src/lib_utils/dictionary.ml
@@ -27,7 +27,7 @@ module Assoc : DICTIONARY = struct
 
   let set ?equal lst a b =
     let equal : 'a -> 'a -> bool =
-      Option.unopt
+      X_option.unopt
         ~default:(=) equal
     in
     let rec aux acc = function
@@ -39,7 +39,7 @@ module Assoc : DICTIONARY = struct
 
   let del ?equal lst a =
     let equal : 'a -> 'a -> bool =
-      Option.unopt
+      X_option.unopt
         ~default:(=) equal
     in
     let rec aux acc = function
diff --git a/src/lib_utils/option.ml b/src/lib_utils/option.ml
deleted file mode 100644
index 4ee7859ff..000000000
--- a/src/lib_utils/option.ml
+++ /dev/null
@@ -1,3 +0,0 @@
-let unopt ~default = function
-  | None -> default
-  | Some x -> x
diff --git a/src/lib_utils/tezos_utils.ml b/src/lib_utils/tezos_utils.ml
index 3c7086378..38bf94f97 100644
--- a/src/lib_utils/tezos_utils.ml
+++ b/src/lib_utils/tezos_utils.ml
@@ -14,7 +14,7 @@ module PP_helpers = PP
 module Location = Location
 
 module List = X_list
-module Option = Tezos_base.TzPervasives.Option
+module Option = X_option
 module Cast = Cast
 module Tuple = Tuple
 module Map = X_map
diff --git a/src/lib_utils/trace.ml b/src/lib_utils/trace.ml
index f39658fca..ca54980f0 100644
--- a/src/lib_utils/trace.ml
+++ b/src/lib_utils/trace.ml
@@ -334,13 +334,13 @@ module Assert = struct
   let assert_equal_int ?msg expected actual =
     let msg =
       let default = Format.asprintf "Not equal int : expected %d, got %d" expected actual in
-      Option.unopt ~default msg in
+      X_option.unopt ~default msg in
     assert_equal ~msg expected actual
 
   let assert_equal_bool ?msg expected actual =
     let msg =
       let default = Format.asprintf "Not equal bool : expected %b, got %b" expected actual in
-      Option.unopt ~default msg in
+      X_option.unopt ~default msg in
     assert_equal ~msg expected actual
 
   let assert_none ?(msg="not a none") opt = match opt with
diff --git a/src/lib_utils/tree.ml b/src/lib_utils/tree.ml
index d76ec20ab..7b4c5886a 100644
--- a/src/lib_utils/tree.ml
+++ b/src/lib_utils/tree.ml
@@ -108,4 +108,14 @@ module Append = struct
     match t with
     | Empty -> None
     | Full t' -> assoc_opt' t' k
+
+  let rec pp' : _ -> _ -> 'a t' -> unit = fun f ppf t' ->
+    match t' with
+    | Leaf x -> Format.fprintf ppf "%a" f x
+    | Node {a;b} -> Format.fprintf ppf "N(%a , %a)" (pp' f) a (pp' f) b
+
+  let pp : _ -> _ -> 'a t -> unit = fun f ppf t ->
+    match t with
+    | Empty -> Format.fprintf ppf "[]"
+    | Full x -> Format.fprintf ppf "[%a]" (pp' f) x
 end
diff --git a/src/lib_utils/x_option.ml b/src/lib_utils/x_option.ml
new file mode 100644
index 000000000..2063463db
--- /dev/null
+++ b/src/lib_utils/x_option.ml
@@ -0,0 +1,6 @@
+include Tezos_stdlib.Option
+
+let lr (a , b) = match (a , b) with
+  | Some x , _ -> Some (`Left x)
+  | None , Some x -> Some (`Right x)
+  | _ -> None