∀ {α : Type u} {x : BEq α} {x_1 : Hashable α} [inst : EquivBEq α] [inst_1 : LawfulHashable α] {l : List α},
  List.Pairwise (fun a b => (a == b) = false) l → (Std.ExtHashMap.unitOfList l).size = l.length