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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 read_gold_standard_file(data_dir, fileroot, encoding=None, cetr=False):
 """ Read the gold standard content file corresponding to identifier ``fileroot`` in the gold standard directory below the root ``data_dir``. Args: data_dir (str) fileroot (str) encoding (str) cetr (bool):
 if True, assume no comments and parse the gold standard to remove tags Returns: List[str, str]: contents string and comments string, respectively """

    fname = os.path.join(
        data_dir, GOLD_STANDARD_DIRNAME, fileroot + GOLD_STANDARD_EXT)
    encodings = (encoding,) if encoding else ('utf-8', 'utf-16', 'iso-8859-1')
    for encoding in encodings:
        try:
            with io.open(fname, mode='rt', encoding=encoding) as f:
                gold_standard = f.read()
            break
        except (UnicodeDecodeError, UnicodeError):
            gold_standard = None

    if not gold_standard:
        return [u'', u'']

    if not cetr:
        content_comments = RE_COMMENTS_DELIM.split(gold_standard, maxsplit=1)
        # if no comments delimiter found, append empty comments string
        if len(content_comments) == 1:
            content_comments = [content_comments[0], u'']
    else:
        tree = etree.fromstring(gold_standard, parser=etree.HTMLParser())
        content_comments = [u' '.join(text_from_subtree(tree)), u'']

    # fix text in case of mangled encodings
    content_comments = [ftfy.fix_encoding(content_comments[0]).strip(),
                        ftfy.fix_encoding(content_comments[1]).strip()]

    return content_comments