Cmdliner_def.Arg_completionCompletion strategies
val value : ?doc:string -> 'a -> 'a directiveval string : ?doc:string -> string -> 'a directiveval files : 'a directiveval dirs : 'a directiveval restart : 'a directiveval message : string -> 'a directiveval raw : string -> 'a directiveval complete_none : 'a tval complete_files : 'a tval complete_dirs : 'a tval complete_paths : 'a tval complete_restart : 'a t