    sig
      val zero : int64
      val one : int64
      val minus_one : int64
      external neg : int64 -> int64 = "%int64_neg"
      external add : int64 -> int64 -> int64 = "%int64_add"
      external sub : int64 -> int64 -> int64 = "%int64_sub"
      external mul : int64 -> int64 -> int64 = "%int64_mul"
      external div : int64 -> int64 -> int64 = "%int64_div"
      external rem : int64 -> int64 -> int64 = "%int64_mod"
      val succ : int64 -> int64
      val pred : int64 -> int64
      val abs : int64 -> int64
      val max_int : int64
      val min_int : int64
      external logand : int64 -> int64 -> int64 = "%int64_and"
      external logor : int64 -> int64 -> int64 = "%int64_or"
      external logxor : int64 -> int64 -> int64 = "%int64_xor"
      val lognot : int64 -> int64
      external shift_left : int64 -> int -> int64 = "%int64_lsl"
      external shift_right : int64 -> int -> int64 = "%int64_asr"
      external shift_right_logical : int64 -> int -> int64 = "%int64_lsr"
      external of_int : int -> int64 = "%int64_of_int"
      external to_int : int64 -> int = "%int64_to_int"
      external of_float : float -> int64 = "int64_of_float"
      external to_float : int64 -> float = "int64_to_float"
      external of_int32 : int32 -> int64 = "%int64_of_int32"
      external to_int32 : int64 -> int32 = "%int64_to_int32"
      external of_nativeint : nativeint -> int64 = "%int64_of_nativeint"
      external to_nativeint : int64 -> nativeint = "%int64_to_nativeint"
      external of_string : string -> int64 = "int64_of_string"
      val to_string : int64 -> string
      external format : string -> int64 -> string = "int64_format"
      external bits_of_float : float -> int64 = "int64_bits_of_float"
      external float_of_bits : int64 -> float = "int64_float_of_bits"
    end