functions.php

<?php
require_once(get_template_directory().'/walkers/bootstrap-nav-walker.php');
require_once(get_template_directory().'/walkers/bootstrap-comment-walker.php');

// Add Thumbnails feature.
add_theme_support( 'post-thumbnails' );

function add_theme_scripts() {
    wp_enqueue_style( 'style', get_stylesheet_uri() );

    // Require bootstrap css.
    wp_enqueue_style( 'bootstrap-min-css', get_stylesheet_directory_uri().'/lib/bootstrap/bootstrap.min.css', array('style'), '4.1.0', 'all');

    // Include Javascripts required for the theme.
    wp_enqueue_script( 'bootstrap-min-js', get_stylesheet_directory_uri().'/lib/bootstrap/bootstrap.bundle.min.js', array ( 'jquery' ), '4.1.0', true);
}

add_action( 'wp_enqueue_scripts', 'add_theme_scripts' );

/* ------------------------------------------------------------------------- */

function mbe_body_class($classes){
    if(is_user_logged_in()){
        $classes[] = 'body-logged-in';

        if(is_admin_bar_showing()){
            $classes[] = 'showing-admin-bar';
        }
    } else{
        $classes[] = 'body-logged-out';
    }
    return $classes;
}

add_filter('body_class', 'mbe_body_class');

/* ------------------------------------------------------------------------- */

register_nav_menus( array(
    'primary' => __( 'Primary Menu', 'Developer Theme primary menu.' ),
) );

//add_theme_support( 'post-formats', array( 'aside', 'gallery', 'link', 'image', 'quote', 'status', 'video', 'audio', 'chat' ) );

$args = array(
    'name'          => "Sidebar",
    'id'            => "sidebar",
    'description'   => '',
    'class'         => '',
    'before_widget' => '<li id="%1$s" class="widget %2$s list-unstyled">',
    'after_widget'  => "</li>\n",
    'before_title'  => '<h2 class="widgettitle">',
    'after_title'   => "</h2>\n",
);



register_sidebar( $args );

/* ------------------------------------------------------------------------- */

function custom_theme_setup() {
    add_theme_support( 'html5', array( 'comment-list' ) );
}
add_action( 'after_setup_theme', 'custom_theme_setup' );