class BlockUser

class BlockUser extends ActionBase {
  
  /**
   * {@inheritdoc}
   */
  public function execute($account = NULL) {
    // Skip blocking user if they are already blocked.
    if ($account !== FALSE && $account->isActive()) {
      // For efficiency manually save the original account before applying any
      // changes.
      $account->original = clone $account;
      $account->block();
      $account->save();
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function access($object, ?AccountInterface $account = NULL, $return_as_object = FALSE) {
    /** @var \Drupal\user\UserInterface $object */
    $access = $object->status
      ->access('edit', $account, TRUE)
      ->andIf($object->access('update', $account, TRUE));
    return $return_as_object ? $access : $access->isAllowed();
  }

}