sig
val any : Kwvalid.t
val notnull : Kwvalid.t
val notblank : Kwvalid.t
val noblanks : Kwvalid.t
val range : ?desc:string -> (char * char) list -> Kwvalid.t
val lowercase : Kwvalid.t
val uppercase : Kwvalid.t
val alphabetic : Kwvalid.t
val alphanumeric : Kwvalid.t
end