∀ {α : Type u} {β : Type v} [inst : BEq α] {l : Std.DHashMap.Internal.AssocList α fun x => β} {a : α}
  {h : Std.DHashMap.Internal.AssocList.contains a l = true},
  Std.DHashMap.Internal.AssocList.get a l h = Std.Internal.List.getValue a l.toList ⋯