∀ {α : Type u} {β : α → Type v} [inst : BEq α] [inst_1 : Hashable α] [EquivBEq α] [LawfulHashable α]
  {l : List ((a : α) × β a)} {k : α},
  (List.map Sigma.fst l).contains k = false →
    (↑(Std.DHashMap.Internal.Raw₀.emptyWithCapacity.insertMany l)).getKey? k = none