Definition rotate {A} (l : list A) n m := sublist (m - n) (Zlength l) l ++
sublist 0 (m - n) l.

Lemma rotate_1 : forall v l n m, 0 <= n < m -> Zlength l < m ->
rotate (upd_Znth 0 (complete m (v :: l)) (vptrofs 0)) n m =
rotate (complete m l) ((n + 1) mod m) m.