drupal 8 show template suggestions code example

Example 1: drupal 8 enable twig debug

// You enable Twig Debugging in services.yml

parameters:
  twig.config:
    debug: true

Example 2: drupal 8 suggestions

function MYMODULE_theme_suggestions_alter(array &$suggestions, array $variables, $hook) {
  if (\Drupal::currentUser()
    ->isAuthenticated() && in_array($hook, array(
    'node',
    'taxonomy_term',
  ))) {
    $suggestions[] = $hook . '__' . 'logged_in';
  }
}