code: def finalize_download(url, download_to_file, content_type, request):
      
      # If format is given, a format check is performed.
      if content_type and content_type not in request.headers['content-type']:
          msg = 'The downloaded file is not of the desired format'
          raise InvenioFileDownloadError(msg)
  
      # Save the downloaded file to desired or generated location.
      to_file = open(download_to_file, 'w')
      try:
          try:
              while True:
                  block = request.read(CFG_FILEUTILS_BLOCK_SIZE)
                  if not block:
                      break
                  to_file.write(block)
          except Exception as e:
              msg = "Error when downloading %s into %s: %s" % \
                    (url, download_to_file, e)
              raise InvenioFileDownloadError(msg)
      finally:
          to_file.close()
  
      # Check Size
      filesize = os.path.getsize(download_to_file)
      if filesize == 0:
          raise InvenioFileDownloadError("%s seems to be empty" % (url,))
  
      # download successful, return the new path
      return download_to_file
docs: Finalizes the download operation by doing various checks, such as format
      type, size check etc.