proposition: Lemma demo_hide_def : forall x:nat, let y := x + x in let z := y in y + 0 = y.
proof: Proof. Proof using. intros. hide_def y. hide_def z. show_def y. show_def z. hide_defs. show_defs. hide_def y. unfold y. show_def. demo. Qed.
imports: TLC(LibTactics) Coq.micromega.Lia