protected function getSeriesRecursive(int $seriesId, array $seen = [], int $depth = 0) : array
{
$series = [];
foreach ($this->getParentSeries($seriesId, $seen, $depth) as $ser) {
if (!empty($ser)) {
$series[] = $ser;
$_seen = $seen;
\array_push($_seen, (int) $ser['seriesid']);
$parents = $this->getSeriesRecursive((int) $ser['seriesid'], $seen, $depth + 1);
foreach ($parents as $par) {
if (!empty($par)) {
$series[] = $par;
}
}
}
}
return $series;
}