Function is_leapyear

python/pyarrow/src/arrow/python/datetime.cc:98–101

    {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};

static bool is_leapyear(int64_t year) {
  return (year & 0x3) == 0 &&  // year % 4 == 0
         ((year % 100) != 0 || (year % 400) == 0);
}

// Calculates the days offset from the 1970 epoch.
static int64_t get_days_from_date(int64_t date_year, int64_t date_month,