∀ {α : Type u} {β : Type v} {m : Std.HashMap.Raw α β} [inst : BEq α] [inst_1 : Hashable α] [EquivBEq α]
  [LawfulHashable α],
  m.WF →
    ∀ {l : List (α × β)} {k k' : α},
      (k == k') = true →
        ∀ {v fallback : β},
          List.Pairwise (fun a b => (a.1 == b.1) = false) l → (k, v) ∈ l → (m.insertMany l).getD k' fallback = v