删除一个account

        Arguments:
            account_cookie {[type]} -- [description]

        Raises:
            RuntimeError -- [description]

def drop_account(self, account_cookie):
        """删除一个account

        Arguments:
            account_cookie {[type]} -- [description]

        Raises:
            RuntimeError -- [description]
        """

        if account_cookie in self.account_list:
            res = self.account_list.remove(account_cookie)
            self.cash.append(
                self.cash[-1] + self.get_account_by_cookie(res).init_cash)
            return True
        else:
            raise RuntimeError(
                'account {} is not in the portfolio'.format(account_cookie)
            )