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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def created_slices(self, user_id=None):
 """List of slices created by this user"""

        if not user_id:
            user_id = g.user.id
        Slice = models.Slice  # noqa
        qry = (
            db.session.query(Slice)
            .filter(
                sqla.or_(
                    Slice.created_by_fk == user_id,
                    Slice.changed_by_fk == user_id,
                ),
            )
            .order_by(Slice.changed_on.desc())
        )
        payload = [{
            'id': o.id,
            'title': o.slice_name,
            'url': o.slice_url,
            'dttm': o.changed_on,
            'viz_type': o.viz_type,
        } for o in qry.all()]
        return json_success(
            json.dumps(payload, default=utils.json_int_dttm_ser))