Hacer opcionales el nombre y email en los comentarios, y ocultar la URL

De esta forma facilitamos a nuestros visitantes la publicación de comentarios y guardaremos menos datos privados.

<?php
function wpb_alter_comment_form_fields($fields) {
 
// Modify Name Field and show that it's Optional 
$fields['author'] = '<p class="comment-form-author">' . '<label for="author">' . __( 'Name (Optional)' ) . '</label> ' . ( $req ? '<span class="required">*</span>' : '' ) .
'<input id="author" name="author" type="text" value="' . esc_attr( $commenter['comment_author'] ) . '" size="30"' . $aria_req . ' /></p>';
 
// Modify Email Field and show that it's Optional
$fields['email'] = '<p class="comment-form-email"><label for="email">' . __( 'Email (Optional)', 'twentythirteen' ) . '</label> ' .
      ( $req ? '<span class="required">*</span>' : '' ) .
      '<input id="email" name="email" type="text" value="' . esc_attr(  $commenter['comment_author_email'] ) .
      '" size="30"' . $aria_req . ' /></p>'; 
 
// This line removes the website URL from comment form.       
      $fields['url'] = '';
 
    return $fields;
}
add_filter('comment_form_default_fields', 'wpb_alter_comment_form_fields');