def _helper_unique_group(all_system_list, tag):
    """
        helper function for group_systems_with_unique_tag_value
        Separate system into lists where each list only has system with unique tag value
    """
    system_list = []
    system_text_list = []
    other_system_list = []
    for ele in all_system_list:
        if ele.find(tag).text not in system_text_list:
            system_list.append(ele)
            system_text_list.append(ele.find(tag).text)
        else:
            other_system_list.append(ele)

    if other_system_list != []:
        other_system_list = _helper_unique_group(other_system_list, tag)

    other_system_list.insert(0, system_list)
    return other_system_list