code: def call_use_cached_files(tup):
    
  
    try:
      cache, key, results_dir = tup
      res = cache.use_cached_files(key, results_dir)
      if res:
        sys.stderr.write('.')
      else:
        sys.stderr.write(' ')
      sys.stderr.flush()
      return res
    except NonfatalArtifactCacheError as e:
      logger.warn('Error calling use_cached_files in artifact cache: {0}'.format(e))
      return False
docs: Importable helper for multi-proc calling of ArtifactCache.use_cached_files on a cache instance.
  
    Multiprocessing map/apply/etc require functions which can be imported, not bound methods.
    To call a bound method, instead call a helper like this and pass tuple of the instance and args.
    The helper can then call the original method on the deserialized instance.
  
    :param tup: A tuple of an ArtifactCache and args (eg CacheKey) for ArtifactCache.use_cached_files.