def jaccard(r_tokens: list, s_tokens: list) -> float:
    """Computes jaccard similarity.

    JAC(r, s) = |r ∩ s| / |r ∪ s|

    Parameters
    ----------
    r_tokens : list
        First token list.
    s_tokens : list
        Second token list.

    Returns
    -------
    Jaccard similarity of r and s.

    """

    r_set = set(r_tokens)
    s_set = set(s_tokens)
    return len(r_set.intersection(s_set)) / len(r_set.union(s_set))