public function getCampaigns()
{
$resource = 'campaigns.json';
$response = $this->sendRequest('GET', $this->getServiceUrl($resource));
$decodedResponseBody = $this->getDecodedBody($response->getBody());
$getCampaignsResponse = new Models\GetCampaignsResponse($decodedResponseBody);
return $getCampaignsResponse->getCampaigns();
}