number of cases 관련 질문입니다

    a = len(list_data)
    new_list_data = []
    for i in range(0,a):
        for j in range(0,a):
            b = str(list_data[i]) + str(list_data[j])
            new_list_data.append(b)

    result = new_list_data
    # ==================================
    return result