protected function get_subscriber( $subscriber ) {

		switch ( $subscriber ) {

			case 'author':
				$order = llms_get_post( $this->post_id );
				if ( ! is_a( $order, 'LLMS_Order' ) ) {
					return false;
				}
				$product = $order->get_product();
				if ( is_a( $product, 'WP_Post' ) ) {
					return false;
				}
				$uid = $product->get( 'author' );
				break;

			case 'student':
				$uid = $this->user_id;
				break;

			default:
				$uid = false;

		}

		return $uid;

	}