work.ex

defmodule Work do
  @spec all_face_cards?(list()) :: boolean()
  def all_face_cards?(list) when is_list(list) do
    list |> Enum.all?(&face_card?/1)
  end

  @spec face_card?(integer()) :: boolean()
  def face_card?(1), do: true
  def face_card?(x) when x >= 10 and x <= 13, do: true
  def face_card?(_), do: false
end