code: def download(self, filename=None, as_type='zip'):
          
          headers = None
          if as_type in ['zip', 'txt', 'json']:
              if as_type == 'zip':
                  if filename is None:
                      raise MissingRequiredInput('Filename must be specified when '
                                                 'downloading IPList as a zip file.')
                  filename = '{}'.format(filename)
              elif as_type == 'txt':
                  headers = {'accept': 'text/plain'}
              elif as_type == 'json':
                  headers = {'accept': 'application/json'}
          
              result = self.make_request(
                  FetchElementFailed,
                  raw_result=True,
                  resource='ip_address_list',
                  filename=filename,
                  headers=headers)
          
              return result.json if as_type == 'json' else result.content
docs: Download the IPList. List format can be either zip, text or
          json. For large lists, it is recommended to use zip encoding.
          Filename is required for zip downloads.
  
          :param str filename: Name of file to save to (required for zip)
          :param str as_type: type of format to download in: txt,json,zip (default: zip)
          :raises IOError: problem writing to destination filename
          :return: None