code: def stats_list(self, list=None, date=None, headers=None):
          
          data = {'stat': 'list'}
          if list is not None:
              data['list'] = list
          if date is not None:
              data['date'] = date
          return self._stats(data, headers)
docs: Retrieve information about your subscriber counts on a particular list, on a particular day.
          http://docs.sailthru.com/api/stat