code: def object(self):
          
          if self.type == EntryType.category:
              return self.category
          elif self.type == EntryType.event:
              return self.event
          elif self.type == EntryType.session:
              return self.session
          elif self.type == EntryType.contribution:
              return self.contribution
          elif self.type == EntryType.subcontribution:
              return self.subcontribution
docs: Return the changed object.