How to use the mintapi.api.Mint.get_rnd function in mintapi

def get_budgets(self):  # {{{
        # Get categories
        categories = self.get_categories()

        # Issue request for budget utilization
        first_of_this_month = date.today().replace(day=1)
        eleven_months_ago = (first_of_this_month - timedelta(days=330)).replace(day=1)
        url = "{}/getBudget.xevent".format(MINT_ROOT_URL)
        params = {
            'startDate': eleven_months_ago.strftime('%m/%d/%Y'),
            'endDate': first_of_this_month.strftime('%m/%d/%Y'),
            'rnd': Mint.get_rnd(),
        }
        response = json.loads(self.get(url, params=params, headers=JSON_HEADER).text)

        # Make the skeleton return structure
        budgets = {
            'income': response['data']['income'][
                str(max(map(int, response['data']['income'].keys())))
            ]['bu'],
            'spend': response['data']['spending'][
                str(max(map(int, response['data']['income'].keys())))
            ]['bu']
        }

        # Fill in the return structure
        for direction in budgets.keys():
            for budget in budgets[direction]:

# Converts the start date into datetime format - must be mm/dd/yy
        try:
            start_date = datetime.strptime(start_date, '%m/%d/%y')
        except (TypeError, ValueError):
            start_date = None
        all_txns = []
        offset = 0
        # Mint only returns some of the transactions at once.  To get all of
        # them, we have to keep asking for more until we reach the end.
        while 1:
            url = MINT_ROOT_URL + '/getJsonData.xevent'
            params = {
                'queryNew': '',
                'offset': offset,
                'comparableType': '8',
                'rnd': Mint.get_rnd(),
            }
            # Specifying accountId=0 causes Mint to return investment
            # transactions as well.  Otherwise they are skipped by
            # default.
            if id > 0 or include_investment:
                params['accountId'] = id
            if include_investment:
                params['task'] = 'transactions'
            else:
                params['task'] = 'transactions,txnfilters'
                params['filterType'] = 'cash'
            result = self.request_and_check(
                url, headers=JSON_HEADER, params=params,
                expected_content_type='text/json|application/json')
            data = json.loads(result.text)
            txns = data['set'][0].get('data', [])

# Get categories
        categories = self.get_categories()

        # Issue request for budget utilization
        today = date.today()
        this_month = date(today.year, today.month, 1)
        last_year = this_month - timedelta(days=330)
        this_month = (str(this_month.month).zfill(2) +
                      '/01/' + str(this_month.year))
        last_year = (str(last_year.month).zfill(2) +
                     '/01/' + str(last_year.year))
        url = "{}/getBudget.xevent".format(MINT_ROOT_URL)
        params = {
            'startDate': last_year,
            'endDate': this_month,
            'rnd': Mint.get_rnd(),
        }
        response = json.loads(self.get(url, params=params, headers=JSON_HEADER).text)

        # Make the skeleton return structure
        budgets = {
            'income': response['data']['income'][
                str(max(map(int, response['data']['income'].keys())))
            ]['bu'],
            'spend': response['data']['spending'][
                str(max(map(int, response['data']['income'].keys())))
            ]['bu']
        }

        # Fill in the return structure
        for direction in budgets.keys():
            for budget in budgets[direction]:

# I can't find any way to retrieve this information other than by
        # doing this stupid one-call-per-account to listTransactions.xevent
        # and parsing the HTML snippet :(
        for account in accounts:
            headers = dict(JSON_HEADER)
            headers['Referer'] = '{}/transaction.event?accountId={}'.format(
                MINT_ROOT_URL, account['id'])

            list_txn_url = '{}/listTransaction.xevent'.format(MINT_ROOT_URL)
            params = {
                'accountId': str(account['id']),
                'queryNew': '',
                'offset': 0,
                'comparableType': 8,
                'acctChanged': 'T',
                'rnd': Mint.get_rnd(),
            }

            response = json.loads(self.get(
                list_txn_url, params=params, headers=headers).text)
            xml = '<div>' + response['accountHeader'] + '</div>'
            xml = xml.replace('–', '-')
            xml = xmltodict.parse(xml)

            account['availableMoney'] = None
            account['totalFees'] = None
            account['totalCredit'] = None
            account['nextPaymentAmount'] = None
            account['nextPaymentDate'] = None

            xml = xml['div']['div'][1]['table']
            if 'tbody' not in xml: