class Aws::S3::FileDownloader::MultipartProgress

def call(part_number, bytes_received, total)
  # part numbers start at 1
  @bytes_received[part_number - 1] = bytes_received
  # part size may not be known until we get the first response
  @part_sizes[part_number - 1] ||= total
  @progress_callback.call(@bytes_received, @part_sizes, @total_size)
end