public function scheduleCampaign($id, \DateTime $runAt = NULL, $tokens = array(), $args = array(), $returnRaw = false)
    {
        $args['id'] = $id;

        if (!empty($runAt)) {
          $args['input']['runAt'] = $runAt->format('c');
        }

        if (!empty($tokens)) {
            $args['input']['tokens'] = $tokens;
        }

        return $this->getResult('scheduleCampaign', $args, false, $returnRaw);
    }