static function setLastId($foreign_id, $timeline, $last_id)
 {
     $tss = self::pkeyGet(array('foreign_id' => $foreign_id, 'timeline' => $timeline));
     if (empty($tss)) {
         $tss = new Twitter_synch_status();
         $tss->foreign_id = $foreign_id;
         $tss->timeline = $timeline;
         $tss->last_id = $last_id;
         $tss->created = common_sql_now();
         $tss->modified = $tss->created;
         $tss->insert();
         return true;
     } else {
         $orig = clone $tss;
         $tss->last_id = $last_id;
         $tss->modified = common_sql_now();
         $tss->update();
         return true;
     }
 }