scratch.py

class Petition_Response(Base):
    __tablename__ = 'wtp_data_petition_responses'
    
    petition_id = Column(String(64), primary_key=True),
    response_id = Column(String(64)),
    association_time = Column( Integer(11))    
    
    response = relationship("Response", backref=backref('association'))
    petition = relationship("Petition", backref=backref('association'))