code: private function getPeriod($requested)
      {
          $month = substr($requested, 0, 6);
          $begin = $this->hlpPeriod->getPeriodFirstDate($month);
          $end = $this->hlpPeriod->getPeriodLastDate($month);
          $result = [$begin, $end];
          return $result;
      }
docs: Return 2 dates (period being/end): first day of the month and today.
  
  @param string $requested 'YYYY', 'YYYYMM' or 'YYYYMMDD'
  @return array