def last_available_business_date(self, asset_manager_id, asset_ids, page_no=None, page_size=None):
        """
        Returns the last available business date for the assets so we know the 
        starting date for new data which needs to be downloaded from data providers.
        
        This method can only be invoked by system user
        """
        self.logger.info('Retrieving last available business dates for assets')
        url = '%s/last-available-business-date' % self.endpoint
        params = {'asset_manager_ids': [asset_manager_id],
                  'asset_ids': ','.join(asset_ids)}
        if page_no:
            params['page_no'] = page_no
        if page_size:
            params['page_size'] = page_size
        response = self.session.get(url, params=params)
        if response.ok:
            self.logger.info("Received %s assets' last available business date", len(response.json()))
            return response.json()
        else:
            self.logger.error(response.text)
            response.raise_for_status()
Returns the last available business date for the assets so we know the 
        starting date for new data which needs to be downloaded from data providers.
        
        This method can only be invoked by system user