End my_MapFold.
(* Next we show the assumptions in the previous section are satisfied if M is a set of maps, neutral is the empty map, op is MapMerge and R is eqmap *)

Lemma my_alist_of_map_lemma_3 :
forall (A : Set) (m : Map A) (a : ad) (y : A),
In (a, y) (alist_of_Map _ m) -> MapGet _ m a = Some y.