def sel_min(self):
    """
    Take maximum id for current level
    :return: None
    """
    # TODO: rewrite for use in multi tree structure
    query = Chain.select(fn.min(Chain.id)).where(Chain.id_parent == self.id_level)
    for c in Chain.select().where(Chain.id_parent == self.id_level).order_by(Chain.id.asc()):
        res = c.id
        return res