code: def download_file(pk):
      
      release_file = models.ReleaseFile.objects.get(pk=pk)
      logging.info("Downloading %s", release_file.url)
  
      proxies = None
      if settings.LOCALSHOP_HTTP_PROXY:
          proxies = settings.LOCALSHOP_HTTP_PROXY
      response = requests.get(release_file.url, stream=True, proxies=proxies)
  
      # Write the file to the django file field
      filename = os.path.basename(release_file.url)
  
      # Setting the size manually since Django can't figure it our from
      # the raw HTTPResponse
      if 'content-length' in response.headers:
          size = int(response.headers['content-length'])
      else:
          size = len(response.content)
  
      # Setting the content type by first looking at the response header
      # and falling back to guessing it from the filename
      default_content_type = 'application/octet-stream'
      content_type = response.headers.get('content-type')
      if content_type is None or content_type == default_content_type:
          content_type = mimetypes.guess_type(filename)[0] or default_content_type
  
      # Using Django's temporary file upload system to not risk memory
      # overflows
      with TemporaryUploadedFile(name=filename, size=size, charset='utf-8',
                                 content_type=content_type) as temp_file:
          temp_file.write(response.content)
          temp_file.seek(0)
  
          # Validate the md5 hash of the downloaded file
          md5_hash = md5_hash_file(temp_file)
          if md5_hash != release_file.md5_digest:
              logging.error("MD5 hash mismatch: %s (expected: %s)" % (
                  md5_hash, release_file.md5_digest))
              return
  
          release_file.distribution.save(filename, temp_file)
          release_file.save()
      logging.info("Complete")
docs: Download the file reference in `models.ReleaseFile` with the given pk.