code: def fill_default_realm(self):
          
          if not getattr(self, 'realms', None):
              # Create a default realm so all hosts without realm will be linked with it
              default = Realm({
                  'realm_name': u'All', 'alias': u'Self created default realm', 'default': '1'
              })
              self.realms = Realms([default])
              logger.warning("No realms defined, I am adding one as %s", default.get_name())
  
          # Check that a default realm (and only one) is defined and get this default realm
          self.realms.fill_default()
docs: Check if a realm is defined, if not
          Create a new one (default) and tag everyone that do not have
          a realm prop to be put in this realm
  
          :return: None