new_contents: import re
  from datetime import date
  
  class Datapoint:
      def __init__(self, recipient, s_date="01.01.1970", value=0.0, comment=""):
          self.__Recipient = recipient
          self.__Date = s_date
          self.__Value = value
          self.__Comment = comment
  
      def get_recipient(self):
          return self.__Recipient
  
      def set_recipient(self, recipient):
          self.__Recipient = recipient
      
      def get_date(self):
          return self.__Date
  
      def set_date(self, s_date):
          try:
              regex = re.compile(r'\d{1,2}\.\d{1,2}\.\d{4}')
              m = regex.match(date)
              if m:
                  date_split = s_date.split(".")
                  self.__Date = date(date_split[0], date_split[1], date_split[2])
              else:
                  raise ValueError
          except ValueError:
              now = date.today()
              self.__Date = now.strftime("%d.%m.%Y")
  
      def get_value(self):
          return self.__Value
  
      def set_value(self, value):
          if value < 0:
              raise ValueError
          else:
              self.__Value = value
  
      def get_comment(self):
          return self.__Comment
  
      def set_comment(self, comment):
          if ";" in comment:
              raise ValueError
          else:
              self.__Comment = comment
  
      def to_String(self):
          return self.__Recipient + ";" + self.__Date + ";" + str(self.__Value) + ";" + self.__Comment
subject: add class Datapoint