[sledge] Add Map.max_binding_exn

Differential Revision: D29441159

fbshipit-source-id: fac47b7cf

sledge/nonstdlib/NSMap.ml

@@ -110,6 +110,7 @@ struct
   let choose_exn = M.choose
   let min_binding = M.min_binding_opt
   let max_binding = M.max_binding_opt
+  let max_binding_exn = M.max_binding
   let mem k m = M.mem k m
   let find_exn k m = M.find k m
   let find k m = M.find_opt k m

sledge/nonstdlib/NSMap_intf.ml

@@ -81,6 +81,7 @@ module type S = sig
 
   val min_binding : 'a t -> (key * 'a) option
   val max_binding : 'a t -> (key * 'a) option
+  val max_binding_exn : 'a t -> key * 'a
   val mem : key -> 'a t -> bool
   val find : key -> 'a t -> 'a option
   val find_exn : key -> 'a t -> 'a