module S3:sig
..end
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