∀ {α : Type u} {β : Type v} {m : Std.HashMap.Raw α β} [inst : BEq α] [inst_1 : Hashable α] [EquivBEq α]
  [LawfulHashable α] [inst_4 : Inhabited α], m.WF → ∀ {k k' : α}, (k == k') = true → m.getKey! k = m.getKey! k'