docs: def _to_dict(self):
          """Return a json dictionary representing this model."""
          _dict = {}
          if hasattr(self, 'source_url') and self.source_url is not None:
              _dict['source_url'] = self.source_url
          if hasattr(self, 'resolved_url') and self.resolved_url is not None:
              _dict['resolved_url'] = self.resolved_url
          if hasattr(self, 'image') and self.image is not None:
              _dict['image'] = self.image
          if hasattr(self, 'error') and self.error is not None:
              _dict['error'] = self.error._to_dict()
          if hasattr(self, 'classifiers') and self.classifiers is not None:
              _dict['classifiers'] = [x._to_dict() for x in self.classifiers]
          return _dict