functions.php

<?php
/**
 * Theme functions.
 *
 * This file is used to load the autoload and bootstrap files necessary
 * for kick-starting the theme.
 *
 * @package Uuups
 */

/**
 * Compatibility check.
 *
 * Check that the site meets the minimum requirements for the theme before
 * proceeding if this is a theme for public release. If building for a client
 * that meets these requirements, this code is unnecessary.
 */
if ( version_compare( $GLOBALS['wp_version'], '4.9', '<' ) || version_compare( PHP_VERSION, '5.6', '<' ) ) {
	require_once get_parent_theme_file_path( 'app/bootstrap-compat.php' );
	return;
}

/**
 * Bootstrap the theme.
 *
 * Load the bootstrap files. Note that autoloading should happen first so that
 * any classes/functions are available that we might need.
 */
require_once get_parent_theme_file_path( 'app/bootstrap-autoload.php' );
require_once get_parent_theme_file_path( 'app/bootstrap-app.php' );