# Pastebin mljZpvjg
    # created_at default set here to safe guard in case it gets missed
    _created_at = sql.Column('created_at', sql.DateTime, nullable=False,
                             default=datetime.datetime.utcnow)
    _expires_at = sql.Column('expires_at', sql.DateTime, nullable=True)
    # set the default to 0, a 0 indicates it is unset.
    created_at_int = sql.Column(sql.DateTimeInt(), nullable=False,
                                default=datetime.datetime.utcnow)
    expires_at_int = sql.Column(sql.DateTimeInt(), nullable=True)
    self_service = sql.Column(sql.Boolean, default=False, nullable=False,
                              server_default='0')

    @hybrid_property
    def created_at(self):
        return self.created_at_int or self._created_at