def download_chunk(key, range)
      instrument :download_chunk, key: key, range: range do
        source = cloudinary_url_for_key(key)
        download_range(source, range)
      end
    end
def download_chunk(key, range)
      instrument :download_chunk, key: key, range: range do
        source = cloudinary_url_for_key(key)
        download_range(source, range)
      end
    end
Return the partial content in the byte +range+ of the file at the +key+.