Hint Rewrite @upd_Znth_app1 using list_solve : sublist.
Hint Rewrite @upd_Znth_app2 using list_solve : sublist.

Lemma Zlength_sublist_correct: forall {A} (l: list A) (lo hi: Z),
0 <= lo <= hi ->
hi <= Zlength l ->
Zlength (sublist lo hi l) = hi - lo.