__construct() public method

Create the client.
public __construct ( $api_key, $secret, string $session_key = null )
$session_key string if you haven't gotten a session key yet, leave this as null and then set it later by just directly accessing the $session_key member variable.
 public function __construct($api_key, $secret, $backend_api_key, $backend_secret_key, $backend_host, $backend_port, $backend_url, $canvas_url, $local_req_uri, $session_key = null)
 {
     parent::__construct($api_key, $secret, $session_key);
     $this->m_backend_api_key = $backend_api_key;
     $this->m_backend_secret_key = $backend_secret_key;
     $this->m_an = Analytics_Utils::instance($backend_api_key, $backend_secret_key, $backend_host, $backend_port, $backend_url, $canvas_url, $local_req_uri);
     //$this->m_an->set_ab_testing_mgr(new AB_Testing_Manager($backend_api_key, $backend_secret_key,
     //$ab_testing_host, $ab_testing_port ));
 }