Returns true if the page appears to be the index page of an svn repository

def is_svn_page(html):
    # type: (Union[str, Text]) -> Optional[Match[Union[str, Text]]]
    """
    Returns true if the page appears to be the index page of an svn repository
    """
    return (re.search(r'<title>[^<]*Revision \d+:', html) and
            re.search(r'Powered by (?:<a[^>]*?>)?Subversion', html, re.I))