first_and_last_day_of_the_month.py

import calendar

def get_first_and_last_day_for_a_year(year_num):
    first_and_last_dates = []
    first_and_last_dates_formatted = []
    for i in range(1, 13):
        _, num_days = calendar.monthrange(year_num, i)
        first_day = datetime.date(year_num, i, 1)
        last_day = datetime.date(year_num, i, num_days)
        first_and_last_dates.append([first_day, last_day])
        formatted_first_and_last_date = [first_day.strftime('%Y-%m-%d')]
        formatted_first_and_last_date.append(last_day.strftime('%Y-%m-%d'))
        first_and_last_dates_formatted.append(formatted_first_and_last_date)
    return first_and_last_dates, first_and_last_dates_formatted

first_and_last_dates = get_first_and_last_day_for_a_year(2016)