Theorem add_0_r : forall n:nat, n + 0 = n. intros n. induction n as [| n' IHn'].- (* n = 0 *) reflexivity.
- (* n = Sn' *) simpl. rewrite -> IHn'. reflexivity. Qed.Theorem plu
ip_r="48.50.31.172" << use regex on this line for evaluate text then assign to ip_rdomain_a="www.linux.org"domain_r="org.linux.www" << use regex on this line for evaluate text then assign to domain_r