Pythonで月末月初の営業日を求める

import datetime
import calendar


def is_business_day(date):
    return date.weekday() < 5 # 5:土、6:日


def get_beginning_of_the_month_business_day(year, month, offset=0):
    first_day = datetime.date(year, month, 1)
    # print(first_day.strftime("%Y/%m/%d"))

    count = 0
    while True:
        if is_business_day(first_day):
            if count >= offset:
                return first_day
            else:
                count = count + 1
        first_day = first_day + datetime.timedelta(days=1)


def get_end_of_the_month_business_day(year, month, offset=0):
    monthrange = calendar.monthrange(year, month)
    day = monthrange[1]
    last_day = datetime.date(year, month, day)
    # print(last_day.strftime("%Y/%m/%d"))

    count = 0
    while True:
        if is_business_day(last_day):
            if count >= offset:
                return last_day
            else:
                count = count + 1
        last_day = last_day - datetime.timedelta(days=1)


if __name__ == "__main__":
    now = datetime.datetime.now()
    print(now.strftime("%Y-%m-%d"))

    print(get_beginning_of_the_month_business_day(now.year, now.month, 0))
    print(get_end_of_the_month_business_day(now.year, now.month, 0))

    print(get_beginning_of_the_month_business_day(now.year, 5, 1))
    print(get_end_of_the_month_business_day(now.year, 5, 1))

$ python business_day.py
2021-04-19
2021-04-01
2021-04-30
2021-05-04
2021-05-28