how could i know who send the signal? e.g. (from class.ticket.php):
$type = array('type' => 'closed');
Signal::send('object.edited', $t, $type);
$type = array('type' => 'assigned', $key => true);
Signal::send('object.edited', $this, $type);
what property in subscribed function i should check to know who send the signal?