Ltac start :=
    red; unfold append_entries_leaderLogs; intros;
    subst; simpl in *; find_higher_order_rewrite;
    update_destruct; subst; rewrite_update; eauto; simpl in *.Ltac prove_in :=
    match goal with
      | [ _ : nwPackets ?net = _,
              _ : In (?p : packet) _ |- _] =>
        assert (In p (nwPackets net)) by (repeat find_rewrite; do_in_app; intuition)
      | [ _ : nwPackets ?net = _,
              _ : pBody ?p = _ |- _] =>
        assert (In p (nwPackets net)) by (repeat find_rewrite; intuition)
    end.

Lemma Prefix_refl : forall A (l : list A), Prefix l l.