/**
* Compares two event instances by start time
*
* @param EventInstance $a Instance
* @param EventInstance $b Instance
* @return int
*/
public static function compareInstancesByStartTime($a, $b)
{
$start_a = $a->getStartTimestamp();
$start_b = $b->getStartTimestamp();
if ($start_a == $start_b) {
return 0;
}
return $start_a < $start_b ? -1 : 1;
}
