sig
val name : 'a Type.t -> 'b Type.t -> string
val module_name : string
val structural_descr :
Structural_descr.t -> Structural_descr.t -> Structural_descr.t
type ('a, 'b) t
val reprs : 'a -> 'b -> ('a, 'b) Type.Polymorphic2_input.t list
end