/**
 * Implements hook_image_style_save().
 */
function {{ machine_name }}_image_style_save($style) {
  // If a module defines an image style and that style is renamed by the user
  // the module should update any references to that style.
  if (isset($style['old_name']) && $style['old_name'] == variable_get('mymodule_image_style', '')) {
    variable_set('mymodule_image_style', $style['name']);
  }
}