functor (A : S5) (B : S5) -> sig type t = { eq : 'a 'b 'c 'd 'e. (('a, 'b, 'c, 'd, 'e) A.t, ('a, 'b, 'c, 'd, 'e) B.t) Type_equal.t; } val witness : Typename.Same_witness_exn_5.t end