old_contents: class Person(object):
      def __init__(self, person_type, person_name, person_surname="", wants_accommodation="N"):
          self.person_name = person_name
          self.person_surname = person_surname
          self.person_type = person_type
          self.wants_accommodation = wants_accommodation
  
      def full_name(self):
          if not isinstance(self.person_name, str) or not isinstance(self.person_surname, str):
              raise ValueError('Only strings are allowed as names')
          else:
              self.full_name = self.person_name + " " + self.person_surname
              return self.full_name
  
new_contents: class Person(object):
      def __init__(self, person_type, person_name, person_surname="", wants_accommodation="N"):
          self.person_name = person_name
          self.person_surname = person_surname
          self.person_type = person_type
          self.wants_accommodation = wants_accommodation
  
      def full_name(self):
          self.full_name = self.person_name + " " + self.person_surname
          return self.full_name
  
subject: Change full name method to stop validating for str type which is repetitive and has been tested elsewhere