如何在SQLAlchemy关系()中使用sortedcontainers.SortedList？

from sortedcontainers import SortedList
from sqlalchemy import Column, Integer, ForeignKey
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship

from sqlalchemy.ext.mutable import MutableList

class SortedListType(MutableList):
    def __init__(self, item_type):
        self.item_type = item_type
        super(SortedListType, self).__init__()

    def append(self, value):
        super(SortedListType, self).append(value)
        self.sort()

    def remove(self, value):
        super(SortedListType, self).remove(value)

    def sort(self):
        super(SortedListType, self).sort()

    def __setitem__(self, index, value):
        super(SortedListType, self).__setitem__(index, value)
        self.sort()

    def __getstate__(self):
        return list(self)

    def __setstate__(self, state):
        self[:] = state

    def __getitem__(self, index):
        return super(SortedListType, self).__getitem__(index)

    def __len__(self):
        return super(SortedListType, self).__len__()

    def __iter__(self):
        return super(SortedListType, self).__iter__()

    def __delitem__(self, index):
        super(SortedListType, self).__delitem__(index)

    def __eq__(self, other):
        return list(self) == other

    def __ne__(self, other):
        return list(self) != other

    def __repr__(self):
        return repr(list(self))

    def __str__(self):
        return str(list(self))

Base = declarative_base()

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    children = Column(SortedListType(Integer))

class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('parent.id'))

parent = Parent()
parent.children = SortedList([3, 1, 2])
session.add(parent)
session.commit()

child = Child()
child.parent = parent
session.add(child)
session.commit()

# 查询parent的children，并按照排序列表的顺序返回
sorted_children = session.query(Parent).filter_by(id=parent.id).first().children
print(sorted_children)