proposition: Lemma subst_hyp_demo : forall (x y x' y' z z' : nat) (P:nat->Prop), (x,y,z) = (x',y',z') -> P x -> P x' -> P y -> P y' -> P z -> P z' -> z = z'.
proof: Proof. Proof using. introv H. intros. subst_hyp_base H. auto. Qed.
imports: TLC(LibTactics) Coq.micromega.Lia