def _validate_time_style(time_style: str) -> None:
    """
    Validate the time style.

    Args:
        time_style (str): The time style to validate.

    Raises:
        ValueError: If `time_style` is not a valid value.

    Returns:
        None
    """
    if time_style not in _get_time_formats_dict():
        raise ValueError(f"time_style must be one of: {', '.join(_get_time_formats_dict().keys())}")

    Validate the time style.

    Args:
        time_style (str): The time style to validate.

    Raises:
        ValueError: If `time_style` is not a valid value.

    Returns:
        None
    
great_tables/_formats.py