Custom Metaboxes

<?php
/*
    Plugin Name: La Pizzeria - Metaboxes
    Plugin URI:
    Description: Añade Metaboxes al Sitio Web
    Version: 1.0.0
    Author: None
    Author URI: http://instagram.com/
    Text Domain: lapizzeria
*/

function lapizzeria_add_metaboxes(){
   add_meta_box('lapizzeria-metaboxes', __('Our Metabox'), 'lapizzeria_design_metaboxes', 'especialidades', 'normal', 'high', null);
}
add_action('add_meta_boxes', 'lapizzeria_add_metaboxes');

function lapizzeria_save_metaboxes($post_id, $post, $update){
  if(!isset($_POST['meta-box-nonce']) || !wp_verify_nonce($_POST['meta-box-nonce'], basename(__FILE__)))
      return $post_id;

  if(!current_user_can('edit_post', $post_id))
      return $post_id;

  if(defined("DOING_AUTOSAVE") && DOING_AUTOSAVE)
      return $post_id;

  $input_metabox = "";
   if(isset($_POST['input-metabox'])){
       $input_metabox = $_POST['input-metabox'];
   }
   update_post_meta($post_id, 'input-metabox', $input_metabox);
   return true;

}
add_action('save_post', 'lapizzeria_save_metaboxes', 10, 3);

// callbacks to create the meta boxes
function lapizzeria_design_metaboxes($post){
    wp_nonce_field(basename(__FILE__), "meta-box-nonce");
    ?>
    <div>
        <label for="input-metabox">Price</label>
        <input type="text" name="input-metabox" placeholder="enter the value" value="<?php echo get_post_meta($post->ID, 'input-metabox', true); ?>">
    </div>
  <?php

}