def convert_to_bool(value_str: str) -> bool:
    """
    Converts string values to their boolean equivalents.
    :param value_str: Value string.
    :return: The boolean value represented by `value_str`, if any.
    :raise: A ValueError if it is not possible to convert the value string to bool.
    """
    conversion_dict = {"true": True, "t": True, "y": True, "false": False, "f": False, "n": False}
    try:
        return conversion_dict[value_str.lower()]
    except KeyError as e:
        raise ValueError(f"Not a boolean value: {value_str}") from e