def valid_time(x: str) -> bool:
    """
    Return ``True`` if ``x`` is a valid H:MM:SS or HH:MM:SS time;
    otherwise return ``False``.
    """
    if isinstance(x, str) and (
        re.match(TIME_PATTERN1, x) or re.match(TIME_PATTERN2, x)
    ):
        return True
    else:
        return False
Return ``True`` if ``x`` is a valid H:MM:SS or HH:MM:SS time;
    otherwise return ``False``.