    sig
      type t
      external repr : 'a -> Obj.t = "%identity"
      external obj : Obj.t -> 'a = "%identity"
      external magic : 'a -> 'b = "%identity"
      external is_block : Obj.t -> bool = "obj_is_block"
      external is_int : Obj.t -> bool = "%obj_is_int"
      external tag : Obj.t -> int = "obj_tag"
      external size : Obj.t -> int = "%obj_size"
      external field : Obj.t -> int -> Obj.t = "%obj_field"
      external set_field : Obj.t -> int -> Obj.t -> unit = "%obj_set_field"
      external new_block : int -> int -> Obj.t = "obj_block"
      external dup : Obj.t -> Obj.t = "obj_dup"
      external truncate : Obj.t -> int -> unit = "obj_truncate"
      val no_scan_tag : int
      val closure_tag : int
      val infix_tag : int
      val object_tag : int
      val abstract_tag : int
      val string_tag : int
      val double_tag : int
      val double_array_tag : int
      val final_tag : int
      val marshal : Obj.t -> string
      val unmarshal : string -> int -> Obj.t * int
    end