proposition: Lemma demo_clears : forall (x y z : nat) (A B : Prop), (x > 0) -> (x <> y) -> (A <-> B) -> True.
proof: Proof. Proof using. introv z Pos Neq Iff. dup 5. clears y. demo. clears x. demo. clears x y. demo. clears Neq A. demo. clears. demo. Qed.
imports: TLC(LibTactics) Coq.micromega.Lia