**（1）strftime**
**（2）datetime.now()**
**（3）時間相加減**
**注意到datetime是模組，datetime模組還包含一個datetime類，通過from datetime import datetime匯入的才是datetime這個類。**
**如果僅匯入import datetime，則必須引用全名datetime.datetime。**
**datetime.now()返回當前日期和時間，其型別是datetime。**
YEAR = int(datetime.datetime.now().year)
features.established_years = datetime.datetime.now
 
().year - int(es_date_str)

date2 = str(datetime.now())
date = datetime.strptime(date.split(' ')[0], format)
date2 = datetime.strptime(date2.split(' ')[0], format)
days_diff = (date2 - date).days

self.nowtime = datetime.now().strftime('%Y-%m-%d %H:%M:%S')

from datetime import timedelta
update_time = datetime.datetime.now
 
() - datetime.timedelta(days=31)

last_time = get_time_now.return_value.strftime('%Y-%m-%d')