       18000
 
   """
-  @spec diff(DateTime.t, DateTime.t) :: Calendar.rata_die
+  @spec diff(DateTime.t, DateTime.t) :: integer()
   def diff(%DateTime{utc_offset: utc_offset1, std_offset: std_offset1} = datetime1,
            %DateTime{utc_offset: utc_offset2, std_offset: std_offset2} = datetime2, unit \\ :seconds) do
     {days1, {parts1, ppd1}} =


  The answer can be returned in any `unit` available from `t:System.time_unit/0`.

  This operation is only possible if both calendars are convertible to `Calendar.ISO`.

  ## Examples


  end

  @doc """
  Subtracts `datetime2` from `datetime1`.

  The answer can be returned in any `unit` available from `t:System.time_unit/0`.

  This function returns the difference in seconds where seconds are measured
  according to `Calendar.ISO`.

  ## Examples

