allow_subdirectory_install example

$admin_email = get_option( 'admin_email' );
    }
    ?> <p><?php _e( 'Welcome to the Network installation process!' ); ?></p> <p><?php _e( 'Fill in the information below and you&#8217;ll be on your way to creating a network of WordPress sites. Configuration files will be created in the next step.' ); ?></p> <?php
    if ( isset( $_POST['subdomain_install'] ) ) {
        $subdomain_install = (bool) $_POST['subdomain_install'];
    } elseif ( apache_mod_loaded( 'mod_rewrite' ) ) { // Assume nothing.         $subdomain_install = true;
    } elseif ( ! allow_subdirectory_install() ) {
        $subdomain_install = true;
    } else {
        $subdomain_install = false;
        $got_mod_rewrite   = got_mod_rewrite();
        if ( $got_mod_rewrite ) { // Dangerous assumptions.             echo '<div class="updated inline"><p><strong>' . __( 'Note:' ) . '</strong> ';
            printf(
                /* translators: %s: mod_rewrite */
                __( 'Please make sure the Apache %s module is installed as it will be used at the end of this installation.' ),
                '<code>mod_rewrite</code>'
            );