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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 _highlight(html):
 """Syntax-highlights HTML-rendered Markdown. Plucks sections to highlight that conform the the GitHub fenced code info string as defined at https://github.github.com/gfm/#info-string. Args: html (str):
 The rendered HTML. Returns: str: The HTML with Pygments syntax highlighting applied to all code blocks. """


    formatter = pygments.formatters.HtmlFormatter(nowrap=True)

    code_expr = re.compile(
        r'<pre><code class="language-(?P<lang>.+?)">(?P<code>.+?)'
        r'</code></pre>', re.DOTALL)

    def replacer(match):
        try:
            lang = match.group('lang')
            lang = _LANG_ALIASES.get(lang, lang)
            lexer = pygments.lexers.get_lexer_by_name(lang)
        except ValueError:
            lexer = pygments.lexers.TextLexer()

        code = match.group('code')

        # Decode html entities in the code. cmark tries to be helpful and
        # translate '"' to '&quot;', but it confuses pygments. Pygments will
        # escape any html entities when re-writing the code, and we run
        # everything through bleach after.
        code = html_parser.HTMLParser().unescape(code)

        highlighted = pygments.highlight(code, lexer, formatter)

        return '<pre>{}</pre>'.format(highlighted)

    result = code_expr.sub(replacer, html)

    return result