docs: def UploadFile(self, fd, offset=0, amount=None):
      """Uploads chunks of a given file descriptor to the transfer store flow.
  
      Args:
        fd: A file descriptor to upload.
        offset: An integer offset at which the file upload should start on.
        amount: An upper bound on number of bytes to stream. If it is `None` then
          the whole file is uploaded.
  
      Returns:
        A `BlobImageDescriptor` object.
      """
      return self._UploadChunkStream(
          self._streamer.StreamFile(fd, offset=offset, amount=amount))