code: def get(self, filename):
          
          timer = Timer()
          self.check_prerequisites()
          with PatchedBotoConfig():
              # Check if the distribution archive is available.
              raw_key = self.get_cache_key(filename)
              logger.info("Checking if distribution archive is available in S3 bucket: %s", raw_key)
              key = self.s3_bucket.get_key(raw_key)
              if key is None:
                  logger.debug("Distribution archive is not available in S3 bucket.")
              else:
                  # Download the distribution archive to the local binary index.
                  # TODO Shouldn't this use LocalCacheBackend.put() instead of
                  #      implementing the same steps manually?!
                  logger.info("Downloading distribution archive from S3 bucket ..")
                  file_in_cache = os.path.join(self.config.binary_cache, filename)
                  makedirs(os.path.dirname(file_in_cache))
                  with AtomicReplace(file_in_cache) as temporary_file:
                      key.get_contents_to_filename(temporary_file)
                  logger.debug("Finished downloading distribution archive from S3 bucket in %s.", timer)
                  return file_in_cache
docs: Download a distribution archive from the configured Amazon S3 bucket.
  
          :param filename: The filename of the distribution archive (a string).
          :returns: The pathname of a distribution archive on the local file
                    system or :data:`None`.
          :raises: :exc:`.CacheBackendError` when any underlying method fails.