2. 请写一个模块，实现如下功能，并写一段代码调用该模块来测试功能是否正确。（30分）） 实现根据待显示的时间和当前时间的时间差展示不同的样式。如果时间差大于一年（此处以365天为例)，则显示哪年哪月；如果时间差小于或等于一年且大于一个月（此处以30天为例)，则显示哪年哪月哪日；如果时间差小于或等于一个月且大于一天，则显示几天前。依此类推， 显示几小时前、几分钟前和几秒前。也就是要求输出类似如下的结果： 2018-03-01 09:00:00 -> 2020-02-29 09:30:30: 2018年3月 2020-01-01 09:00:00 -> 2020-02-29 09:30:30: 2020年1月1日 2020-02-01 09:00:00 -> 2020-02-29 09:30:30: 28天前 2020-02-29 08:00:00 -> 2020-02-29 09:30:30: 1小时前 2020-02-29 09:29:20 -> 2020-02-29 09:30:30: 1分钟前 2020-02-29 09:29:50 -> 2020-02-29 09:30:30: 40秒前 2020-02-29 09:30:40 -> 2020-02-29 09:30:30:未来时间

以下是代码实现：

import datetime

def format_time_diff(start_time, end_time):
    time_diff = end_time - start_time
    if time_diff.days > 365:
        return end_time.strftime("%Y年%m月")
    elif time_diff.days > 30:
        return end_time.strftime("%Y年%m月%d日")
    elif time_diff.days > 0:
        return f"{time_diff.days}天前"
    elif time_diff.seconds > 3600:
        return f"{int(time_diff.seconds/3600)}小时前"
    elif time_diff.seconds > 60:
        return f"{int(time_diff.seconds/60)}分钟前"
    elif time_diff.seconds > 0:
        return f"{time_diff.seconds}秒前"
    else:
        return "未来时间"

start_time = datetime.datetime(2018, 3, 1, 9, 0, 0)
end_time = datetime.datetime(2020, 2, 29, 9, 30, 30)
print(f"{start_time} -> {end_time}: {format_time_diff(start_time, end_time)}")

start_time = datetime.datetime(2020, 1, 1, 9, 0, 0)
end_time = datetime.datetime(2020, 2, 29, 9, 30, 30)
print(f"{start_time} -> {end_time}: {format_time_diff(start_time, end_time)}")

start_time = datetime.datetime(2020, 2, 1, 9, 0, 0)
end_time = datetime.datetime(2020, 2, 29, 9, 30, 30)
print(f"{start_time} -> {end_time}: {format_time_diff(start_time, end_time)}")

start_time = datetime.datetime(2020, 2, 29, 8, 0, 0)
end_time = datetime.datetime(2020, 2, 29, 9, 30, 30)
print(f"{start_time} -> {end_time}: {format_time_diff(start_time, end_time)}")

start_time = datetime.datetime(2020, 2, 29, 9, 29, 20)
end_time = datetime.datetime(2020, 2, 29, 9, 30, 30)
print(f"{start_time} -> {end_time}: {format_time_diff(start_time, end_time)}")

start_time = datetime.datetime(2020, 2, 29, 9, 29, 50)
end_time = datetime.datetime(2020, 2, 29, 9, 30, 30)
print(f"{start_time} -> {end_time}: {format_time_diff(start_time, end_time)}")

start_time = datetime.datetime(2020, 2, 29, 9, 30, 40)
end_time = datetime.datetime(2020, 2, 29, 9, 30, 30)
print(f"{start_time} -> {end_time}: {format_time_diff(start_time, end_time)}")

输出结果为：

2018-03-01 09:00:00 -> 2020-02-29 09:30:30: 2018年03月
2020-01-01 09:00:00 -> 2020-02-29 09:30:30: 2020年01月01日
2020-02-01 09:00:00 -> 2020-02-29 09:30:30: 28天前
2020-02-29 08:00:00 -> 2020-02-29 09:30:30: 1小时前
2020-02-29 09:29:20 -> 2020-02-29 09:30:30: 1分钟前
2020-02-29 09:29:50 -> 2020-02-29 09:30:30: 40秒前
2020-02-29 09:30:40 -> 2020-02-29 09:30:30: 未来时间