docs: def send_batch(messages, api_key=None, secure=None, test=None, **request_args):
      '''Send a batch of messages.
  
      :param messages: Messages to send.
      :type message: A list of `dict` or :class:`Message`
      :param api_key: Your Postmark API key. Required, if `test` is not `True`.
      :param secure: Use the https scheme for the Postmark API.
          Defaults to `True`
      :param test: Use the Postmark Test API. Defaults to `False`.
      :param \*\*request_args: Keyword arguments to pass to
          :func:`requests.request`.
      :rtype: :class:`BatchSendResponse`
      '''
      return _default_pyst_batch_sender.send(messages=messages, api_key=api_key,
                                             secure=secure, test=test,
                                             **request_args)