protected function export(): void {

		// Unexport first
		$this->unexport();

		// TODO review like PHPi
		file_put_contents(
			static::ROOT_FILESYSTEM . static::EXPORT,
			"{$this->linuxNumber}"
		);

		// Check
		if ( ! file_exists( static::ROOT_FILESYSTEM . static::GPIO . $this->linuxNumber ) ) {
			throw new ExportException( "Problem with export. GPIO {$this->linuxNumber} not found" );
		}
		$this->isExported = TRUE;
	}