def capital_first_transform(word: str, index: int):
    """
    Capital-case a single word

    Parameters
    ----------
    word : str
        Word to capital-case
    index : int
        Index of word in original string of words. If `index == 0`, the word
        will be capitalized, otherwise it will be lower-cased.

    Returns
    -------
    w : str
        Transformed word.
    """
    return word.capitalize() if index == 0 else word.lower()
