<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def send(self, **extra):
 """ Sends email batch. :return: Information about sent emails. :rtype: `list` """

        emails = self.as_dict(**extra)
        responses = [self._manager._send_batch(*batch) for batch in chunks(emails, self.MAX_SIZE)]
        return sum(responses, [])