Python implementation of the date of judgment and add and subtract operations in detail

#====================================================
#Time related
#====================================================
 
def if_workday(day_str, separator=""):
    """
    if a day is workday
    
    :param day_str: string of a day
    :param separator: separator of year, month and day, default is empty
    :return: True: is workday; False: not workday
    """
    spec = "%Y" + separator + "%m" + separator + "%d"
    day = (day_str, spec).date()
    # Monday == 0 ... Sunday == 6
    if () in [0, 1, 2, 3, 4]:
        return True
    else:
        return False
 
def if_weekend(day_str, separator=""):
    """
    if a day is weekend
    
    :param day_str: string of a day
    :param separator: separator of year, month and day, default is empty
    :return: True: is weekend; False: not weekend
    """
    spec = "%Y" + separator + "%m" + separator + "%d"
    day = (day_str, spec).date()
    # Monday == 0 ... Sunday == 6
    if () in [5, 6]:
        return True
    else:
        return False
 
def is_week_lastday():
    '''
    Determine if today is the weekend，return the day of the week as an integer,Monday is 0 and Sunday is 6
    
    :return:
    '''
    
    now = (() + (hours=8))
    # If it's Sunday
    todayIndex = ()
    # If today is Sunday, return True
    if todayIndex == 6:
        print("todayIndex={},It's the weekend....".format(todayIndex))
        return True
    else:
        print("todayIndex={},It's the week. {}，It's not the weekend....".format(todayIndex,int(todayIndex+1)))
        return False
    
def is_week_whichday(dayIndex=6):
    '''
    Determine which day of the week it is today, Monday is 0 and the weekend is 6, return the day of the week as an integer,Monday is 0 and Sunday is 6

    :return.
    '''
    
    now = (() + (hours=8))
    # If it's Sunday
    todayIndex = ()
    # If today is Sunday, return True
    if todayIndex == dayIndex:
        print("todayIndex={},It's the week. {}，It's not Chow. {}...".format(todayIndex, int(todayIndex+1),int(dayIndex+1)))
        return True
    else:
        print("todayIndex={},It's the week. {}，It's not Chow. {}...".format(todayIndex,int(todayIndex+1),int(dayIndex+1)))
        return False
 
def is_month_lastday():
    '''
    # Determine if today is the end of the month
    
    :return:
    '''
    
    # Get the date of the 1st of the month
    start_date = ().replace(day=1)
    # Get the total number of days in the month (i.e., the date of the last day)
    _, days_in_month = (start_date.year, start_date.month)
 
    todayIndex = ("%d", ())
    
    # If it's the weekend, return True
    if int(todayIndex) == int(days_in_month):
        print("start_date={},todayIndex={},days_in_month={},It's the end of the month....".format(start_date,todayIndex, days_in_month))
        return True
    else:
        print("start_date={},todayIndex={},days_in_month={},It's not the end of the month....".format(start_date,todayIndex , days_in_month))
        return False
 
def get_this_week_start():
    '''
    Get the date of the first day of the week

    :return.
    '''
    now = ()
    this_week_start = now - timedelta(days=())
    this_week_end = now + timedelta(days=6 - ())
    print('--- this_week_start = {} this_week_end = {}'.format(this_week_start, this_week_end))
    print('--- this_week_start = {} '.format(this_week_start))
    return this_week_start
    
def get_this_week_end():
    '''
    # Get the last day of the week
    
    :return:
    '''
    
    now = ()
    this_week_start = now - timedelta(days=())
    this_week_end = now + timedelta(days=6 - ())
    print('--- this_week_start = {} this_week_end = {}'.format(this_week_start, this_week_end))
    print('--- this_week_end = {}'.format(this_week_end))
    return this_week_end
 
def get_last_month_start(now = ()):
    
    now = (now, "%Y-%m-%d")
    # First and last day of the month
    this_month_start = (, , 1)
    this_month_end = (,  + 1, 1) - timedelta(days=1) + (hours=23, minutes=59, seconds=59)
    # print('--- this_month_start = {} this_month_end = {}'.format(this_month_start, this_month_end))
    
    # First and last day of the previous month
    last_month_end = this_month_start - timedelta(days=1)+ (hours=23, minutes=59, seconds=59)
    last_month_start = (last_month_end.year, last_month_end.month, 1)
    # print('--- last_month_end = {} last_month_start = {}'.format(last_month_end, last_month_start))
    print('--- last_month_start = {}'.format(last_month_start))
    return last_month_start
 
def get_last_month_end(now = ()):
    now = (now, "%Y-%m-%d")
    # First and last day of the month
    this_month_start = (, , 1)
    this_month_end = (,  + 1, 1) - timedelta(days=1) + (hours=23, minutes=59, seconds=59)
    # print('--- this_month_start = {} this_month_end = {}'.format(this_month_start, this_month_end))
    
    # First and last day of the previous month
    last_month_end = this_month_start - timedelta(days=1) + (hours=23, minutes=59, seconds=59)
    last_month_start = (last_month_end.year, last_month_end.month, 1)
    # print('--- last_month_end = {} last_month_start = {}'.format(last_month_end, last_month_start))
    print('--- last_month_end = {} '.format(last_month_end))
    return last_month_end
 
def get_this_month_start(now = ()):
    now = (now, "%Y-%m-%d")
    # First and last day of the month
    this_month_start = (, , 1)
    this_month_end = (,  + 1, 1) - timedelta(days=1) + (hours=23, minutes=59, seconds=59)
    # print('--- this_month_start = {} this_month_end = {}'.format(this_month_start, this_month_end))
    
    # First and last day of the previous month
    last_month_end = this_month_start - timedelta(days=1) + (hours=23, minutes=59, seconds=59)
    last_month_start = (last_month_end.year, last_month_end.month, 1)
    # print('--- last_month_end = {} last_month_start = {}'.format(last_month_end, last_month_start))
    print('--- this_month_start = {} '.format(this_month_start))
    return this_month_start
 
def get_this_month_end(now = ()):
    now=(now, "%Y-%m-%d")
    # First and last day of the month
    this_month_start = (, , 1)
    # this_month_end = (,  + 1, 1) - timedelta(days=1) + (hours=23, minutes=59, seconds=59)
    
    if  < 12:
        this_month_end = (,  + 1, 1) - timedelta(days=1) + (hours=23, minutes=59, seconds=59)
    elif   >= 12:
        this_month_end = (,  , +30) + (hours=23, minutes=59, seconds=59)
 
        
    # print('--- this_month_start = {} this_month_end = {}'.format(this_month_start, this_month_end))
    
    # First and last day of the previous month
    last_month_end = this_month_start - timedelta(days=1) + (hours=23, minutes=59, seconds=59)
    last_month_start = (last_month_end.year, last_month_end.month, 1)
    # print('--- last_month_end = {} last_month_start = {}'.format(last_month_end, last_month_start))
    # print('--- this_month_end = {} '.format(this_month_end))
    return str(this_month_end)
 
# Get each day from a time period, with customizable intervals.
def get_every_day(start = '2018-01-01',end = '2021-01-01',daysCount=1):
    '''
    Get each day from a time period, with customizable intervals.

    :param start: str type, start time, e.g. '2018-01-01'
    :param end: str type, end time, e.g. '2021-01-01'
    :param daysCount: int type, every time interval, default is 1 day
    :return.
    '''
    datestart = (start, '%Y-%m-%d')
    dateend = (end, '%Y-%m-%d')
    
    date_list=[]
    while datestart < dateend:
        datestart += (days=daysCount)
        date_str=str(('%Y-%m-%d'))
        # print('date_str={}'.format(date_str))
        date_list.append(date_str)
 
    print('date_list={}'.format(date_list))
    return date_list
 
# Get each month from a time period, with customizable time intervals.
def getBetweenEveryMonth(begin_date,end_date):
    date_list = []
    begin_date = (begin_date, "%Y-%m-%d")
    end_date = (end_date, "%Y-%m-%d")
    # end_date = (('%Y-%m-%d', (())), "%Y-%m-%d")
    while begin_date <= end_date:
        date_str = begin_date.strftime("%Y-%m-%d")
        begin_date = add_months_start(begin_date, 1)
        date_end=get_this_month_end(date_str)
        date_list.append((date_str+' 00:00:00',date_end))
        
    print('date_list={}'.format(date_list))
    return date_list
 
 
def add_months_start(dt, months):
    month = int( - 1 + months)
    year = int( + month / 12)
    month = int(month % 12 + 1)
    day = min(, (year, month)[1])
    return (year=year, month=month, day=day)
 
def add_months_end(dt, months):
    month = int( - 1 + months)
    year = int( + month / 12)
    month = int(month % 12 + 1)
    day = max(, (year, month)[1])
    return (year=year, month=month, day=day)