public function relateTo($destination, $label)
{
static::$links[$label][] = array('origin' => $this->id, 'destination' => $destination->id, 'label' => $label);
if (isset($this->node['index'])) {
static::$indexedId[$this->id] = 1;
}
static::$lastLink =& static::$links[$label][count(static::$links[$label]) - 1];
$this->isLink = true;
return $this;
}