def is_web_url(string):
    """Check to see if string is an validly-formatted web url."""
    assert isinstance(string, basestring)
    parsed_url = urllib.parse.urlparse(string)
    return (
        (
            parsed_url.scheme.lower() == 'http'
            or parsed_url.scheme.lower() == 'https'
        )
        and parsed_url.netloc
    )
Check to see if string is an validly-formatted web url.