addYears
Creates a copy of @datetime and adds the specified number of years to the copy. Add negative values to subtract years.
As with g_date_time_add_months(), if the resulting date would be 29th February on a non-leap year, the day will be clamped to 28th February.
Return
the newly created #GDateTime which should be freed with g_date_time_unref(), or null
Since
2.26
Parameters
years
the number of years