如何使用sqlalchemy查询多对多关系？

from sqlalchemy import Column, Integer, String, Table, ForeignKey
from sqlalchemy.orm import relationship
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

user_role = Table('user_role', Base.metadata,
    Column('user_id', Integer, ForeignKey('user.id')),
    Column('role_id', Integer, ForeignKey('role.id'))
)

class User(Base):
    __tablename__ = 'user'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    roles = relationship('Role', secondary=user_role, backref='users')

class Role(Base):
    __tablename__ = 'role'
    id = Column(Integer, primary_key=True)
    name = Column(String)

user = session.query(User).filter_by(name='John').first()
roles = user.roles

role = session.query(Role).filter_by(name='Admin').first()
users = role.users

users = session.query(User).join(User.roles).filter(Role.name == 'Admin').all()

users = session.query(User).join(User.roles).filter(Role.name.in_(['Admin', 'Editor'])).all()