docs: def get(self):
          """
          Get a JSON-ready representation of this Mail object.
  
          :returns: This Mail object, ready for use in a request body.
          :rtype: dict
          """
          mail = {
              'from': self._get_or_none(self.from_email),
              'subject': self._get_or_none(self.subject),
              'personalizations': [p.get() for p in self.personalizations or []],
              'content': [c.get() for c in self.contents or []],
              'attachments': [a.get() for a in self.attachments or []],
              'template_id': self._get_or_none(self.template_id),
              'sections': self._flatten_dicts(self.sections),
              'headers': self._flatten_dicts(self.headers),
              'categories': [c.get() for c in self.categories or []],
              'custom_args': self._flatten_dicts(self.custom_args),
              'send_at':  self._get_or_none(self.send_at),
              'batch_id': self._get_or_none(self.batch_id),
              'asm': self._get_or_none(self.asm),
              'ip_pool_name': self._get_or_none(self.ip_pool_name),
              'mail_settings': self._get_or_none(self.mail_settings),
              'tracking_settings': self._get_or_none(self.tracking_settings),
              'reply_to': self._get_or_none(self.reply_to),
          }
  
          return {key: value for key, value in mail.items()
                  if value is not None and value != [] and value != {}}