def sha256file(abspath, nbytes=<NUM_LIT:0>, chunk_size=DEFAULT_CHUNK_SIZE):
return get_file_fingerprint(abspath, hashlib.sha256, nbytes=nbytes, chunk_size=chunk_size)<EOL>
Return sha256 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