/**
* Merge two DateRange objects into one DateRange object.
*
* @param DateRange $dateRange Daterange object to merge.
* @return DateRange DateRange object that is merged.
*/
public function merge(DateRange $dateRange)
{
$dateRange1 = $this->extract();
$dateRange2 = $dateRange->extract();
$resultDateRange = array_unique(array_merge($dateRange1, $dateRange2), SORT_NUMERIC);
return new DateRange(min($resultDateRange), max($resultDateRange));
}