def basic_ttr(n_terms, n_words):
    """ Type-token ratio (TTR) computed as t/w, where t is the number of unique
    terms/vocab, and w is the total number of words.
    (Chotlos 1944, Templin 1957)
    """
    if n_words == 0:
        return 0
    return n_terms / n_words