code: long getYearMonthMillis(int year, int month) {
          long millis = getYearMillis(year);
          millis += getTotalMillisByYearMonth(year, month);
          return millis;
      }
docs: Get the milliseconds for the start of a month.
  
  @param year The year to use.
  @param month The month to use
  @return millis from 1970-01-01T00:00:00Z