`sig
type t = BatBitSet.t
exception Negative_index of string
val empty : unit -> t
val create : int -> t
val create_full : int -> t
val copy : t -> t
val clone : t -> t
val set : t -> int -> unit
val unset : t -> int -> unit
val put : t -> bool -> int -> unit
val toggle : t -> int -> unit
val is_set : t -> int -> bool
val compare : t -> t -> int
val equals : t -> t -> bool
val count : t -> int
val enum : t -> int BatEnum.t
val intersect : t -> t -> unit
val unite : t -> t -> unit
val differentiate : t -> t -> unit
val differentiate_sym : t -> t -> unit
val inter : t -> t -> t
val union : t -> t -> t
val diff : t -> t -> t
val sym_diff : t -> t -> t
val print : 'a BatInnerIO.output -> t -> unit
end`