code: def promote(self, level=None):
          
  
          if level is None:
  
              if len(self.fields) < 2:
                  if self.level in ('region', 'division', 'state', 'ua'):
                      cls = self.get_class('us')
                  else:
                      return None
              else:
                  cls = self.get_class(self.fields[-2])
          else:
              cls = self.get_class(level)
  
          d = dict(self.__dict__.items())
          d['sl'] = self.sl
  
          return cls(**d)
docs: Convert to the next higher level summary level