text: import calendar
  import pandas as pd
  
  def expiry(year, root='path'):
      df_holidays = pd.read_csv(root + 'indian_holidays.csv')
      df_holidays['date'] = pd.to_datetime(df_holidays['date'], format='%Y-%m-%d',infer_datetime_format=True).dt.strftime('%d-%m-%Y')
      "Last Thu of the Month is a holiday. The list is manually created. Checked till 2015, if you want to add the support beyond 2015 then add the dates in 'holiday_list', also if possible share "
      holiday_list = df_holidays['date'].tolist()
  
      expiry_list = ['Empty']  # since list starts from 0 this is a hacky way to align expiry_list[1] = first month
      for n in range(1, 13):
          month = n
          last_day = calendar.monthrange(year, month)[1]
          day_month = calendar.weekday(year, month, last_day)  # 0 is monday and 3 is Thu
          week = [3, 4, 5, 6, 0, 1, 2]
          days = -1
  
          for i in week:
              days += 1
              if i == day_month:
                  break
  
          date_thu = last_day - days
          "zfill function formats single digits to double digits by adding a leading zero which is needed in NSE option url, comment it if not needed"
          month_1 = str(month).zfill(2)
          date_1 = str(date_thu).zfill(2)
          expiry = (date_1) + "-" + (month_1) + "-" + str(year)
          "check if last Thu of the month (expiry day) is not holiday, if it is holiday then shift the date by one to Wed"
          for h in holiday_list:
              if expiry == h:
                  date2 = str(date_thu - 1).zfill(2)
                  expiry = (date2) + "-" + (month_1) + "-" + str(year)
          # print(expiry)
          expiry_list.append(expiry)
      return (expiry_list)