wp-73k/src/sidebars.php

<?php

namespace WP_73k;

/**
 * Register widget area.
 */
add_action( 'widgets_init', function () {

  register_sidebar( [
    'name'          => esc_html( 'Sidebar' ),
    'id'            => 'sidebar',
    'description'   => '',
    'before_widget' => '<section id="%1$s" class="widget %2$s">',
    'after_widget'  => '</section>',
    'before_title'  => '<h4 class="widget-title">',
    'after_title'   => '</h4>',
  ] );

} );