Parse a Uri from a urllib namedtuple.

def _parse_uri_ssh(unt):
    """Parse a Uri from a urllib namedtuple."""
    if '@' in unt.netloc:
        user, host_port = unt.netloc.split('@', 1)
    else:
        user, host_port = None, unt.netloc

    if ':' in host_port:
        host, port = host_port.split(':', 1)
    else:
        host, port = host_port, None

    if not user:
        user = None
    if not port:
        port = smart_open_ssh.DEFAULT_PORT
    else:
        port = int(port)

    return Uri(scheme=unt.scheme, uri_path=unt.path, user=user, host=host, port=port)