if not os.path.isfile(filePath):

              raise koji.GenericError('no file "%s" output by task %i' % (fileName, taskID))

          # Let the caller handler any IO or permission errors

              if isinstance(offset, str):

                  offset = int(offset)

              if offset != None and offset > 0:

          if volume and volume != 'DEFAULT':

              dlopts['volume'] = volume

          result = self.callMethod('downloadTaskOutput', taskID, fileName, **dlopts)

          return base64.decodestring(result.encode('ascii'))