Type.Polymorphic3_inputSee module Polymorphic_input: very same functions with two additional arguments corresponding to the second and third type variables.
val structural_descr :
Structural_descr.t ->
Structural_descr.t ->
Structural_descr.t ->
Structural_descr.tval reprs : 'a -> 'b -> 'c -> ('a, 'b, 'c) t list