def url_to_host(url):
regex_url = r"<STR_LIT>" +r"<STR_LIT>" +r"<STR_LIT>" +r"<STR_LIT>" +r"<STR_LIT>"<EOL>m = re.match(regex_url, url, re.IGNORECASE)<EOL>if m and m.group(<NUM_LIT:3>):<EOL><INDENT>return url[m.start(<NUM_LIT:3>): m.end(<NUM_LIT:3>)]<EOL><DEDENT>else:<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>
convert a url to a host (ip or domain)

    :param url: url string
    :returns: host: domain name or ipv4/v6 address
    :rtype: str
    :raises: ValueError: given an illegal url that without a ip or domain name