Service/Calc/Forecast/Z/Register.php
private function getPeriod($period)
    {
        /* get current month as MONTH period */
        if (!$period) {
            $month = $this->hlpPeriod->getPeriodCurrent(null, 0, \Praxigento\Core\Api\Helper\Period::TYPE_MONTH);
            /* get current date then get yesterday date as end of period */
            $begin = $this->hlpPeriod->getPeriodFirstDate($month);
            $today = $this->hlpPeriod->getPeriodCurrent();
            $end = $this->hlpPeriod->getPeriodPrev($today);
        } else {
            $month = $period;
            $begin = $this->hlpPeriod->getPeriodFirstDate($month);
            $end = $this->hlpPeriod->getPeriodLastDate($month);
        }
        $result = [$begin, $end];
        return $result;
    }
private function getPeriod($period)
    {
        /* get current month as MONTH period */
        if (!$period) {
            $month = $this->hlpPeriod->getPeriodCurrent(null, 0, \Praxigento\Core\Api\Helper\Period::TYPE_MONTH);
            /* get current date then get yesterday date as end of period */
            $begin = $this->hlpPeriod->getPeriodFirstDate($month);
            $today = $this->hlpPeriod->getPeriodCurrent();
            $end = $this->hlpPeriod->getPeriodPrev($today);
        } else {
            $month = $period;
            $begin = $this->hlpPeriod->getPeriodFirstDate($month);
            $end = $this->hlpPeriod->getPeriodLastDate($month);
        }
        $result = [$begin, $end];
        return $result;
    }
Return 2 dates (period being/end): first day of the month and yesterday.

@param string|null $period 'YYYYMM'
@return array