sig
type ('a, 'b, 'c, 'd) writer =
'a Type_class.writer0 -> ('b, 'c, 'd) Type_class.S2.writer
type ('a, 'b, 'c, 'd) reader =
'a Type_class.reader0 -> ('b, 'c, 'd) Type_class.S2.reader
type ('a, 'b, 'c, 'd) t = 'a Type_class.t0 -> ('b, 'c, 'd) Type_class.S2.t
end