def last_index(_list, _value):
    """Finds index of value in reversed list and calculates the correct index

    Args:
        _list (list): List of values
        _value (str): Value to be found

    Returns:
        int: Index of value in list

    Raises:
        ValueError: If value was not found in list
    """
    return len(_list) - _list[-1::-1].index(_value) - 1