Return a json dictionary representing this model.

def _to_dict(self):
        """Return a json dictionary representing this model."""
        _dict = {}
        if hasattr(self, 'status') and self.status is not None:
            _dict['status'] = self.status
        if hasattr(self, 'model_id') and self.model_id is not None:
            _dict['model_id'] = self.model_id
        if hasattr(self, 'language') and self.language is not None:
            _dict['language'] = self.language
        if hasattr(self, 'description') and self.description is not None:
            _dict['description'] = self.description
        if hasattr(self, 'workspace_id') and self.workspace_id is not None:
            _dict['workspace_id'] = self.workspace_id
        if hasattr(self, 'version') and self.version is not None:
            _dict['version'] = self.version
        if hasattr(
                self,
                'version_description') and self.version_description is not None:
            _dict['version_description'] = self.version_description
        if hasattr(self, 'created') and self.created is not None:
            _dict['created'] = datetime_to_string(self.created)
        return _dict