public final static function create_parallel_site_links($fromrun, $torun) {
        global $CFG;

        // Create site symlink if necessary.
        clearstatcache();
        for ($i = $fromrun; $i <= $torun; $i++) {
            // Don't create links for specified sites, as they should be accessible.
            if (!empty($CFG->behat_parallel_run['behat_wwwroot'][$i - 1]['behat_wwwroot'])) {
                continue;
            }
            $link = $CFG->dirroot.'/'.BEHAT_PARALLEL_SITE_NAME.$i;
            clearstatcache();
            if (file_exists($link)) {
                if (!is_link($link) || !is_dir($link)) {
                    echo "File exists at link location ($link) but is not a link or directory!" . PHP_EOL;
                    return false;
                }
            } else if (!symlink($CFG->dirroot, $link)) {
                // Try create link in case it's not already present.
                echo "Unable to create behat site symlink ($link)" . PHP_EOL;
                return false;
            }
        }
        return true;
    }