type t

val pp : Format.formatter -> t -> unit

val _a : t
(** a - user is flagged as away **)

val _i : t
(** i - marks a users as invisible **)

val _w : t
(** w - user receives wallops **)

val _r : t
(** r - restricted user connection **)

val _o : t
(** o - operator flag **)

val _O : t
(** O - local operator flag **)

val _s : t
(** s - marks a user for receipt of server notices **)

val all : t list -> t
val filter : t -> t -> t

val of_char : char -> t
val of_string : string -> t
val of_bitmask_string : ?allowed:t -> string -> t

type diff

val pp_diff : Format.formatter -> t -> unit

val ( ~+ ) : t -> diff
val ( ~- ) : t -> diff
val ( ^ ) : t -> diff -> t
val diff_of_string : string -> t