WC_Gateway_Paypal::init_api PHP Method

    protected function init_api()
    {
        include_once dirname(__FILE__) . '/includes/class-wc-gateway-paypal-api-handler.php';
        WC_Gateway_Paypal_API_Handler::$api_username = $this->get_option('api_username');
        WC_Gateway_Paypal_API_Handler::$api_password = $this->get_option('api_password');
        WC_Gateway_Paypal_API_Handler::$api_signature = $this->get_option('api_signature');
        WC_Gateway_Paypal_API_Handler::$sandbox = $this->testmode;
    }