Hint Rewrite @sublist_nil' using list_solve: sublist.
Hint Rewrite @app_nil_l : sublist.
Hint Rewrite @Zlength_rev : sublist.
Hint Rewrite @sublist_rejoin' using list_solve : sublist.

Lemma upd_Znth_Zlength {A} i (l:list A) v: 0<=i < Zlength l ->
Zlength (upd_Znth i l v) = Zlength l.