proposition: Lemma iter_scons {X: Type} {x: X} {f: nat -> X} {n m: nat} : Nat.iter n (scons x) f (n + m) = f m.
proof: Proof. elim: n m f; first done. move=> n IH m f /=. by apply: IH. Qed.
imports: List Lia Undecidability.SystemF.SysF Undecidability.SystemF.Autosubst.syntax Undecidability.SystemF.Autosubst.unscoped Undecidability.SystemF.Util.Facts ssreflect ssrbool ssrfun