def __jaccard_similarity(set_a=None, set_b=None):
    """
    This function calculates jaccard similarity

    :param set_a: (list) Python list of items
    :param set_b: (list) Python list of second items
    :return: (float) jaccard similarity between set_a and set_b
    """
    x = set_a
    y = set_b
    intersection_cardinality = len(set.intersection(*[set(x), set(y)]))
    union_cardinality = len(set.union(*[set(x), set(y)]))
    return intersection_cardinality / float(union_cardinality)
