docs: def send_scheduled_messages(priority=None, ignore_unknown_messengers=False, ignore_unknown_message_types=False):
      """Sends scheduled messages.
  
      :param int, None priority: number to limit sending message by this priority.
      :param bool ignore_unknown_messengers: to silence UnknownMessengerError
      :param bool ignore_unknown_message_types: to silence UnknownMessageTypeError
      :raises UnknownMessengerError:
      :raises UnknownMessageTypeError:
      """
      dispatches_by_messengers = Dispatch.group_by_messengers(Dispatch.get_unsent(priority=priority))
  
      for messenger_id, messages in dispatches_by_messengers.items():
          try:
              messenger_obj = get_registered_messenger_object(messenger_id)
              messenger_obj._process_messages(messages, ignore_unknown_message_types=ignore_unknown_message_types)
          except UnknownMessengerError:
              if ignore_unknown_messengers:
                  continue
              raise