       31
 
   """
+  @doc since: "1.4.0"
   @spec days_in_month(year, month) :: 28..31
   @impl true
   def days_in_month(year, month)

      "-0099-01-31"

  """
  @spec date_to_string(year, month, day) :: String.t()
  @impl true
  def date_to_string(year, month, day) do

      "02:02:02.000002"

  """
  @doc since: "1.5.0"
  @spec time_to_string(
          Calendar.hour(),
          Calendar.minute(),
