Instance Inhabitant_hist_el : Inhabitant hashtable_hist_el := HGet 0 0.

Lemma add_three : forall lr HT l (Hlr : Zlength lr = 3)
(Hhists : Forall (fun '(h, ls) => add_events empty_map [HAdd 1 1 (Znth 0 ls); HAdd 2 1 (Znth 1 ls);
HAdd 3 1 (Znth 2 ls)] h) lr) (Hlens : Forall (fun '(_, ls) => Zlength ls = 3) lr)
(Hl : hist_list (maps_add (map fst lr)) l) (HHT : apply_hist empty_map l = Some HT)
(Hdisj : all_disjoint (map fst lr)),
Zlength (filter id (concat (map snd lr))) = 3.