Ast_helper.Const

`sig
val char : char -> Parsetree.constant
val string : ?quotation_delimiter:string -> string -> Parsetree.constant
val integer : ?suffix:char -> string -> Parsetree.constant
val int : ?suffix:char -> int -> Parsetree.constant
val int32 : ?suffix:char -> int32 -> Parsetree.constant
val int64 : ?suffix:char -> int64 -> Parsetree.constant
val nativeint : ?suffix:char -> nativeint -> Parsetree.constant
val float : ?suffix:char -> string -> Parsetree.constant
end`