∀ {α : Type u} {β : Type v} {m : Std.HashMap.Raw α β} [inst : BEq α] [inst_1 : Hashable α] [inst_2 : EquivBEq α]
  [inst_3 : LawfulHashable α] (h : m.WF) {a : α} {h' : (m.getKey? a).isSome = true}, (m.getKey? a).get h' = m.getKey a ⋯