public function __construct(DateTime $begin, DateTime $end)
 {
     // @todo Throw an Exception if either date is in the past.
     // @todo Throw an Exception if end is today.
     // begin is allowed to be today.
     parent::__construct($begin, $end);
 }
 public function __construct(DateTime $begin, DateTime $end)
 {
     // @todo Throw an Exception if either date is in the future.
     // @todo Throw an Exception if begin is today.
     // end is allowed to be today.
     parent::__construct($begin, $end);
     // Reverse the array for historical reports so the newest snapshots
     // are first.
     $this->snapshots = array_reverse($this->snapshots);
 }