def get_jaccard_index(
    p_pos: float, p_feature: float, p_pos_feature: float, total_count: int
) -> float:
    """
    Returns the Jaccard Index of a feature, an
    intersection-over-union measure used for gauging similarity and
    diversity of sample sets.
    https://en.wikipedia.org/wiki/Jaccard_index

    :param p_pos: The probability of the positive outcome in the dataset.
    :type p_pos: float
    :param p_feature: The probability of the feature in the dataset.
    :type p_feature: float
    :param p_pos_feature: The probability of the positive outcome and the
        feature in the dataset.
    :type p_pos_feature: float
    :param total_count: The total number of observations in the dataset.
    :type total_count: int
    :return: The Jaccard Index of the feature.
    :rtype: float
    """
    return p_pos_feature / (p_feature + p_pos - p_pos_feature)