Section ListMaps.
Context {A B : Type} {A_eq : EqDec A} {d : Inhabitant B}.
Definition map_Znth i (L : A -> option (list B)) k := option_map (fun v => Znth i v) (L k).

Lemma map_Znth_single : forall i (k : A) (v : list B),
map_Znth i (singleton k v) = singleton k (Znth i v).