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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def call_use_cached_files(tup):
 """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. """


  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