public static function definePrestoThemeAsDefault() {
    // Set presto_theme as default.
    Drupal::configFactory()
      ->getEditable('system.theme')
      ->set('default', 'presto_theme')
      ->save();

    // Set seven as admin theme.
    Drupal::configFactory()
      ->getEditable('system.theme')
      ->set('admin', 'seven')
      ->save();
  }
public static function definePrestoThemeAsDefault() {
    // Set presto_theme as default.
    Drupal::configFactory()
      ->getEditable('system.theme')
      ->set('default', 'presto_theme')
      ->save();

    // Set seven as admin theme.
    Drupal::configFactory()
      ->getEditable('system.theme')
      ->set('admin', 'seven')
      ->save();
  }
public static function definePrestoThemeAsDefault ( ) { // Set presto_theme as default. Drupal :: configFactory ( ) -> getEditable ( 'system.theme' ) -> set ( 'default' , 'presto_theme' ) -> save ( ) ; // Set seven as admin theme. Drupal :: configFactory ( ) -> getEditable ( 'system.theme' ) -> set ( 'admin' , 'seven' ) -> save ( ) ; }
Define Presto Theme as Default. Used by the batch during install process.

@throws \Drupal\Core\Config\ConfigValueException
Define Presto Theme as Default . Used by the batch during install process .