code: def sha512file(abspath, nbytes=0, chunk_size=DEFAULT_CHUNK_SIZE):
      
      return get_file_fingerprint(abspath, hashlib.sha512, nbytes=nbytes, chunk_size=chunk_size)
docs: Return sha512 hash value of a piece of a file
  
      Estimate processing time on:
  
      :param abspath: the absolute path to the file
      :param nbytes: only has first N bytes of the file. if 0 or None,
        hash all file