∀ {α : Type u} {x : BEq α} {x_1 : Hashable α} {β : Type v} [EquivBEq α] [LawfulHashable α] {l : List (α × β)},
  List.Pairwise (fun a b => (a.1 == b.1) = false) l → (Std.DHashMap.Const.ofList l).size = l.length