def urlopen(url, data=None, timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
            *, cafile=None, capath=None, cadefault=False):
    global _opener	# this could be the custom default opener
    if cafile or capath or cadefault:	# if we choose to do a certififcate check
        if not _have_ssl:
            raise ValueError('SSL support not available')
        context = ssl._create_stdlib_context(cert_reqs=ssl.CERT_REQUIRED,
                                             cafile=cafile,
                                             capath=capath)	# create new context
        https_handler = HTTPSHandler(context=context, check_hostname=True) # create new handler with check_hostname = True
        opener = build_opener(https_handler)	# build new opener with check_hostname = True
    elif _opener is None:
        _opener = opener = build_opener()
    else:
        opener = _opener
    return opener.open(url, data, timeout)