public function add_subtitle_field($post)
 {
     if ($post->post_type == 'product') {
         global $post;
         $postID = $post->ID;
         $value = get_product_subtitle($postID);
         $pvalue = __('Subtitle', WCPS_TXT);
         echo '<div id="subtitlediv">';
         echo '<label for="subtitle"><strong> ' . $pvalue . ' : </strong> </lable>';
         echo '<input type="text" autocomplete="off" spellcheck="true" id="subtitle"  size="50" name="product_subtitle" value="' . $value . '" placeholder="' . $pvalue . '">';
         echo '</div>';
     }
 }
 public function get_subtitle($post_id)
 {
     $value = get_product_subtitle($post_id);
     return $value;
 }
 function the_product_subtitle($id)
 {
     $value = get_product_subtitle($id);
     echo $value;
 }