add bootstrap class to checkout fields woocommerce

add_filter('woocommerce_form_field_args',  'wc_form_field_args',10,3);
  function wc_form_field_args($args, $key, $value) {
  $args['input_class'] = array( 'form-control' );
  return $args;
}/**
 * Adding bootstrap classes to woocommerce checkout form
 *
 * @param $fields
 * @return mixed
 */
function wti_add_bootstrap_to_checkout_fields($fields) {
    foreach ($fields as &$fieldset) {
        foreach ($fieldset as &$field) {
            // Add form-group class around the label and the input
            $field['class'][] = 'form-group';
 
            // Add form-control to the actual input
            $field['input_class'][] = 'form-control';
        }
    }
 
    return $fields;
}
 
add_filter('woocommerce_checkout_fields', 'wti_add_bootstrap_to_checkout_fields');