code: def is_first_root(self):
          
          if self.parent:
              return False
          if self._is_first_root is not None:
              return self._is_first_root
          first_root_id = cache.get('PAGE_FIRST_ROOT_ID')
          if first_root_id is not None:
              self._is_first_root = first_root_id == self.id
              return self._is_first_root
          try:
              first_root_id = Page.objects.root().values('id')[0]['id']
          except IndexError:
              first_root_id = None
          if first_root_id is not None:
              cache.set('PAGE_FIRST_ROOT_ID', first_root_id)
          self._is_first_root = self.id == first_root_id
          return self._is_first_root
docs: Return ``True`` if this page is the first root pages.