new_contents: def days_diff(date1, date2):
      
      def days(date):
          y, m, d = date
          correction = m <= 2
          y -= correction; m += 12*correction - 3
          return d + (153*m + 2)//5 + \
                      365*y + y//4 - y//100 + y//400
          
      return abs(days(date1) - days(date2))
  
subject: Create days-diff.py