    sig
      external raise : exn -> 'a = "%raise"
      exception Exit
      val invalid_arg : string -> 'a
      val failwith : string -> 'a
      external ( = ) : 'a -> 'a -> bool = "%equal"
      external ( <> ) : 'a -> 'a -> bool = "%notequal"
      external ( < ) : 'a -> 'a -> bool = "%lessthan"
      external ( > ) : 'a -> 'a -> bool = "%greaterthan"
      external ( <= ) : 'a -> 'a -> bool = "%lessequal"
      external ( >= ) : 'a -> 'a -> bool = "%greaterequal"
      external compare : 'a -> 'a -> int = "compare"
      val min : 'a -> 'a -> 'a
      val max : 'a -> 'a -> 'a
      external ( == ) : 'a -> 'a -> bool = "%eq"
      external ( != ) : 'a -> 'a -> bool = "%noteq"
      external not : bool -> bool = "%boolnot"
      external ( && ) : bool -> bool -> bool = "%sequand"
      external ( & ) : bool -> bool -> bool = "%sequand"
      external ( || ) : bool -> bool -> bool = "%sequor"
      external ( or ) : bool -> bool -> bool = "%sequor"
      external ( ~- ) : int -> int = "%negint"
      external succ : int -> int = "%succint"
      external pred : int -> int = "%predint"
      external ( + ) : int -> int -> int = "%addint"
      external ( - ) : int -> int -> int = "%subint"
      external ( * ) : int -> int -> int = "%mulint"
      external ( / ) : int -> int -> int = "%divint"
      external ( mod ) : int -> int -> int = "%modint"
      val abs : int -> int
      val max_int : int
      val min_int : int
      external ( land ) : int -> int -> int = "%andint"
      external ( lor ) : int -> int -> int = "%orint"
      external ( lxor ) : int -> int -> int = "%xorint"
      val lnot : int -> int
      external ( lsl ) : int -> int -> int = "%lslint"
      external ( lsr ) : int -> int -> int = "%lsrint"
      external ( asr ) : int -> int -> int = "%asrint"
      external ( ~-. ) : float -> float = "%negfloat"
      external ( +. ) : float -> float -> float = "%addfloat"
      external ( -. ) : float -> float -> float = "%subfloat"
      external ( *. ) : float -> float -> float = "%mulfloat"
      external ( /. ) : float -> float -> float = "%divfloat"
      external ( ** ) : float -> float -> float = "power_float" "pow" "float"
      external sqrt : float -> float = "sqrt_float" "sqrt" "float"
      external exp : float -> float = "exp_float" "exp" "float"
      external log : float -> float = "log_float" "log" "float"
      external log10 : float -> float = "log10_float" "log10" "float"
      external cos : float -> float = "cos_float" "cos" "float"
      external sin : float -> float = "sin_float" "sin" "float"
      external tan : float -> float = "tan_float" "tan" "float"
      external acos : float -> float = "acos_float" "acos" "float"
      external asin : float -> float = "asin_float" "asin" "float"
      external atan : float -> float = "atan_float" "atan" "float"
      external atan2 : float -> float -> float = "atan2_float" "atan2" "float"
      external cosh : float -> float = "cosh_float" "cosh" "float"
      external sinh : float -> float = "sinh_float" "sinh" "float"
      external tanh : float -> float = "tanh_float" "tanh" "float"
      external ceil : float -> float = "ceil_float" "ceil" "float"
      external floor : float -> float = "floor_float" "floor" "float"
      external abs_float : float -> float = "%absfloat"
      external mod_float : float -> float -> float = "fmod_float" "fmod" "float"
      external frexp : float -> float * int = "frexp_float"
      external ldexp : float -> int -> float = "ldexp_float"
      external modf : float -> float * float = "modf_float"
      external float : int -> float = "%floatofint"
      external float_of_int : int -> float = "%floatofint"
      external truncate : float -> int = "%intoffloat"
      external int_of_float : float -> int = "%intoffloat"
      val infinity : float
      val neg_infinity : float
      val nan : float
      val max_float : float
      val min_float : float
      val epsilon_float : float
      type fpclass = FP_normal | FP_subnormal | FP_zero | FP_infinite | FP_nan
      external classify_float : float -> Pervasives.fpclass = "classify_float"
      val ( ^ ) : string -> string -> string
      external int_of_char : char -> int = "%identity"
      val char_of_int : int -> char
      external ignore : 'a -> unit = "%ignore"
      val string_of_bool : bool -> string
      val bool_of_string : string -> bool
      val string_of_int : int -> string
      external int_of_string : string -> int = "int_of_string"
      val string_of_float : float -> string
      external float_of_string : string -> float = "float_of_string"
      external fst : 'a * 'b -> 'a = "%field0"
      external snd : 'a * 'b -> 'b = "%field1"
      val ( @ ) : 'a list -> 'a list -> 'a list
      type in_channel
      and out_channel
      val stdin : Pervasives.in_channel
      val stdout : Pervasives.out_channel
      val stderr : Pervasives.out_channel
      val print_char : char -> unit
      val print_string : string -> unit
      val print_int : int -> unit
      val print_float : float -> unit
      val print_endline : string -> unit
      val print_newline : unit -> unit
      val prerr_char : char -> unit
      val prerr_string : string -> unit
      val prerr_int : int -> unit
      val prerr_float : float -> unit
      val prerr_endline : string -> unit
      val prerr_newline : unit -> unit
      val read_line : unit -> string
      val read_int : unit -> int
      val read_float : unit -> float
      type open_flag =
          Open_rdonly
        | Open_wronly
        | Open_append
        | Open_creat
        | Open_trunc
        | Open_excl
        | Open_binary
        | Open_text
        | Open_nonblock
      val open_out : string -> Pervasives.out_channel
      val open_out_bin : string -> Pervasives.out_channel
      val open_out_gen :
        Pervasives.open_flag list -> int -> string -> Pervasives.out_channel
      val flush : Pervasives.out_channel -> unit
      val flush_all : unit -> unit
      val output_char : Pervasives.out_channel -> char -> unit
      val output_string : Pervasives.out_channel -> string -> unit
      val output : Pervasives.out_channel -> string -> int -> int -> unit
      val output_byte : Pervasives.out_channel -> int -> unit
      val output_binary_int : Pervasives.out_channel -> int -> unit
      val output_value : Pervasives.out_channel -> 'a -> unit
      val seek_out : Pervasives.out_channel -> int -> unit
      val pos_out : Pervasives.out_channel -> int
      val out_channel_length : Pervasives.out_channel -> int
      val close_out : Pervasives.out_channel -> unit
      val set_binary_mode_out : Pervasives.out_channel -> bool -> unit
      val open_in : string -> Pervasives.in_channel
      val open_in_bin : string -> Pervasives.in_channel
      val open_in_gen :
        Pervasives.open_flag list -> int -> string -> Pervasives.in_channel
      val input_char : Pervasives.in_channel -> char
      val input_line : Pervasives.in_channel -> string
      val input : Pervasives.in_channel -> string -> int -> int -> int
      val really_input : Pervasives.in_channel -> string -> int -> int -> unit
      val input_byte : Pervasives.in_channel -> int
      val input_binary_int : Pervasives.in_channel -> int
      val input_value : Pervasives.in_channel -> 'a
      val seek_in : Pervasives.in_channel -> int -> unit
      val pos_in : Pervasives.in_channel -> int
      val in_channel_length : Pervasives.in_channel -> int
      val close_in : Pervasives.in_channel -> unit
      val set_binary_mode_in : Pervasives.in_channel -> bool -> unit
      type 'a ref = { mutable contents : 'a; }
      external ref : 'a -> 'a Pervasives.ref = "%makemutable"
      external ( ! ) : 'a Pervasives.ref -> 'a = "%field0"
      external ( := ) : 'a Pervasives.ref -> 'a -> unit = "%setfield0"
      external incr : int Pervasives.ref -> unit = "%incr"
      external decr : int Pervasives.ref -> unit = "%decr"
      val exit : int -> 'a
      val at_exit : (unit -> unit) -> unit
      val unsafe_really_input :
        Pervasives.in_channel -> string -> int -> int -> unit
      val do_at_exit : unit -> unit
    end