unless Version.match?(System.version, ">= 1.3.0 or ~> 1.3.0-dev") do
  defmodule Calendar do
    @moduledoc File.read!("README.md")

    @doc false
    defmacro __using__(_opts) do
       %{file: file, line: line} = __CALLER__
       :elixir_errors.warn(line, file, "use Calendar is deprecated!")
      quote do
        alias Calendar.DateTime
        alias Calendar.DateTime.Interval
        alias Calendar.AmbiguousDateTime
        alias Calendar.NaiveDateTime
        alias Calendar.Date
        alias Calendar.Time
        alias Calendar.TimeZoneData
        alias Calendar.TzPeriod
        alias Calendar.Strftime
      end
    end
  end
end