∀ {α : Type u} [inst : BEq α] [inst_1 : Hashable α] {m : Std.HashMap.Raw α Unit} [EquivBEq α] [LawfulHashable α],
  m.WF → ∀ {l : List α} {k : α}, k ∈ m → (m.insertManyIfNewUnit l).getKey? k = m.getKey? k