public static function getInstance(HttpClient $transport = null)
    {
        if (is_null(self::$client)) {
            self::$client = new self();
        
            if (! is_null($transport)) {
                self::$client->setTransport($transport);
            }
        }
        
        return self::$client;
    }
public static function getInstance(HttpClient $transport = null)
    {
        if (is_null(self::$client)) {
            self::$client = new self();
        
            if (! is_null($transport)) {
                self::$client->setTransport($transport);
            }
        }
        
        return self::$client;
    }
public static function getInstance ( HttpClient $ transport = null ) { if ( is_null ( self :: $ client ) ) { self :: $ client = new self ( ) ; if ( ! is_null ( $ transport ) ) { self :: $ client -> setTransport ( $ transport ) ; } } return self :: $ client ; }
Return a singleton instance of the class
@param GuzzleHttp\Client $transport
@return Arrowsphere\Client\xAC
Return a singleton instance of the class