code: public function toMail($notifiable)
      {
          return (new MailMessage)
              ->subject(__('confirmation::confirmation.confirmation_subject'))
              ->line(__('confirmation::confirmation.confirmation_subject_title'))
              ->line(__('confirmation::confirmation.confirmation_body'))
              ->action(__('confirmation::confirmation.confirmation_button'),
                  url("register/confirm/$notifiable->confirmation_code"));
      }
docs: Get the mail representation of the notification.
  
  @param  mixed  $notifiable
  @return \Illuminate\Notifications\Messages\MailMessage