How to sort comments in Pony

TestPony.py

# encoding=utf-8
__author__ = "Quazi Nafiul Islam"

from pony import orm

# orm.sql_debug(True)
db = orm.Database()
db.bind('sqlite', 'todo_api.db', create_db=True)


class Post(db.Entity):

    name = orm.Required(unicode)
    comments = orm.Set("Comment")


class Comment(db.Entity):

    entry = orm.Required(unicode)
    post = orm.Required(Post)

db.generate_mapping(create_tables=True)

with orm.db_session:

    p = Post(name="Cheese")
    comm1 = Comment(entry="Dude, your post sucks", post=p)
    comm2 = Comment(entry="No, this post is awesome", post=p)
    comm3 = Comment(entry="Who died and made you king?", post=p)

    p2 = Post(name="I love Pony")
    comm7 = Comment(entry="Dude, your post sucks", post=p2)
    comm21 = Comment(entry="No, this post is awesome", post=p2)
    comm77 = Comment(entry="Who died and made you king?", post=p2)

with orm.db_session:

    print {
        p.name: sorted(p.comments, key=lambda x: x.id) for p in Post.select()
    }