def list_a_minus_list_b(list_a, list_b):
    """This method assumes input is two lists with unique elements aka sets.

    It then returns all unique elements in list_a, not present in list_b.

    :param list_a:
    :param list_b:
    :return: list of elements only in list_a OR an empty list
    """
    return list(set(list_a) - set(list_b))