nth_nth' {A} (l : list A) (n : nat) (H : (n < length l)%nat) : nth l n = Some (nth' l n H). Proof. exact (nth_lt l n H).2. Defined.
Require Import Basics.Overture Basics.Tactics Basics.PathGroupoids Basics.Trunc Require Import Types.Paths Types.Unit Types.Prod Types.Sigma Types.Sum