code: public function confirm($confirmation_code)
      {
          $model = $this->guard()->getProvider()->createModel();
  
          $user = $model->where('confirmation_code', $confirmation_code)->firstOrFail();
  
          $user->confirmation_code = null;
          $user->confirmed_at = now();
          $user->save();
  
          event(new Confirmed($user));
  
          return $this->confirmed($user)
              ?: redirect($this->redirectAfterConfirmationPath())->with('confirmation', __('confirmation::confirmation.confirmation_successful'));
      }
docs: Confirm a user with a given confirmation code.
  
  @param $confirmation_code
  @return \Illuminate\Http\RedirectResponse