OptParse.Opt

`sig exception No_value exception Option_error of string * string exception Option_help type 'a t = { option_set : string -> string list -> unit; option_set_value : 'a -> unit; option_get : unit -> 'a option; option_metavars : string list; option_defhelp : string option; } val get : 'a OptParse.Opt.t -> 'a val set : 'a OptParse.Opt.t -> 'a -> unit val opt : 'a OptParse.Opt.t -> 'a option val is_set : 'a OptParse.Opt.t -> bool val value_option : string -> 'a option -> (string -> 'a) -> (exn -> string -> string) -> 'a OptParse.Opt.t val callback_option : string -> (string -> 'a) -> (exn -> string -> string) -> ('a -> unit) -> unit OptParse.Opt.t end`