code: def _fetch_chunker(self, uri, chunk_size, size, obj_size):
          
          pos = 0
          total_bytes = 0
          size = size or obj_size
          max_size = min(size, obj_size)
          while True:
              endpos = min(obj_size, pos + chunk_size - 1)
              headers = {"Range": "bytes=%s-%s" % (pos, endpos)}
              resp, resp_body = self.api.method_get(uri, headers=headers,
                      raw_content=True)
              pos = endpos + 1
              if not resp_body:
                  # End of file
                  return
              yield resp_body
              total_bytes += len(resp_body)
              if total_bytes >= max_size:
                  return
docs: Returns a generator that returns an object in chunks.