∀ {α : Type u} [inst : BEq α] [inst_1 : Hashable α] {β : Type v} (m : Std.DHashMap.Internal.Raw₀ α fun x => β)
  [EquivBEq α] [LawfulHashable α],
  (↑m).WF →
    ∀ {l : List (α × β)} {k fallback : α},
      (List.map Prod.fst l).contains k = false →
        (↑(Std.DHashMap.Internal.Raw₀.Const.insertMany m l)).getKeyD k fallback = m.getKeyD k fallback