fact: Fixpoint ith3_pair {m : nat} {As : Vector.t A m} {As' : Vector.t A' m} {il : ilist3 As} (ilp : ilist3_pair il As') (n : Fin.t m) {struct n} : C (Vector.nth As' n) (ith3 il n) .
imports: Coq.Lists.List Coq.Strings.String Coq.Arith.Arith Fiat.Common.ilist Fiat.Common.ilist3