Python之獲取上月的第一天以及最後一天

from datetime import datetime, date
from dateutil.relativedelta import relativedelta

this_month = date.today()
last_month = date.today() - relativedelta(months=1)
first_day = (date(last_month.year, last_month.month, 1)).strftime('%Y-%m-%d')
last_day = (date(this_month.year, this_month.month, 1) - relativedelta(days=1)).strftime('%Y-%m-%d')