∀ {α : Type u} {β : α → Type v} {m : Std.DHashMap.Raw α β} [inst : BEq α] [inst_1 : Hashable α] [EquivBEq α]
  [LawfulHashable α] [inst_4 : Inhabited α],
  m.WF → ∀ {k a : α} {v : β k}, (m.insertIfNew k v).getKey! a = if (k == a) = true ∧ k ∉ m then k else m.getKey! a