async def update(self: T, _columns: Optional[List[str]] = None, **kwargs: Any) -> T:
        """
        Performs update of Model instance in the database.
        Fields can be updated before or you can pass them as kwargs.

        Sends pre_update and post_update signals.

        Sets model save status to True.

        :param _columns: list of columns to update, if None all are updated
        :type _columns: List
        :raises ModelPersistenceError: If the pk column is not set

        :param kwargs: list of fields to update as field=value pairs
        :type kwargs: Any
        :return: updated Model
        :rtype: Model
        """
        if kwargs:
            self.update_from_dict(kwargs)

        if not self.pk:
            raise ModelPersistenceError(
                "You cannot update not saved model! Use save or upsert method."
            )

        await self.signals.pre_update.send(
            sender=self.__class__, instance=self, passed_args=kwargs
        )
        self_fields = self._extract_model_db_fields()
        self_fields.pop(self.get_column_name_from_alias(self.ormar_config.pkname))
        if _columns:
            self_fields = {k: v for k, v in self_fields.items() if k in _columns}
        if self_fields:
            self_fields = self.translate_columns_to_aliases(self_fields)
            expr = self.ormar_config.table.update().values(**self_fields)
            expr = expr.where(self.pk_column == getattr(self, self.ormar_config.pkname))

            await self.ormar_config.database.execute(expr)
        self.set_save_status(True)
        await self.signals.post_update.send(sender=self.__class__, instance=self)
        return self

        Performs update of Model instance in the database.
        Fields can be updated before or you can pass them as kwargs.

        Sends pre_update and post_update signals.

        Sets model save status to True.

        :param _columns: list of columns to update, if None all are updated
        :type _columns: List
        :raises ModelPersistenceError: If the pk column is not set

        :param kwargs: list of fields to update as field=value pairs
        :type kwargs: Any
        :return: updated Model
        :rtype: Model
        
ormar/models/model.py