Sets HTTP status header.

function status_header( $code, $description = '' ) {
	if ( ! $description ) {
		$description = get_status_header_desc( $code );
	}

	if ( empty( $description ) ) {
		return;
	}

	$protocol      = wp_get_server_protocol();
	$status_header = "$protocol $code $description";
	if ( function_exists( 'apply_filters' ) ) {

		/**
		 * Filters an HTTP status header.
		 *
		 * @since 2.2.0
		 *
		 * @param string $status_header HTTP status header.
		 * @param int    $code          HTTP status code.
		 * @param string $description   Description for the status code.
		 * @param string $protocol      Server protocol.
		 */
		$status_header = apply_filters( 'status_header', $status_header, $code, $description, $protocol );
	}

	if ( ! headers_sent() ) {
		header( $status_header, true, $code );
	}
}