<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_sent(self, expired=False, for_all=False):
 """Retreve information on previously sent transfers. :param expired: Whether or not to return expired transfers. :param for_all: Get transfers for all users. Requires a Filemail Business account. :type for_all: bool :type expired: bool :rtype: ``list`` of :class:`pyfilemail.Transfer` objects """


        method, url = get_URL('get_sent')

        payload = {
            'apikey': self.session.cookies.get('apikey'),
            'logintoken': self.session.cookies.get('logintoken'),
            'getexpired': expired,
            'getforallusers': for_all
            }

        res = getattr(self.session, method)(url, params=payload)

        if res.status_code == 200:
            return self._restore_transfers(res)

        hellraiser(res.json())