text: from sqlalchemy import Column, ForeignKey, Integer, String
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import relationship
  from sqlalchemy import create_engine
  
  Base = declarative_base()
  
  class Page(Base):
      __tablename__ = 'page'
      id = Column(Integer, primary_key=True)
      url = Column(String, unique=True)
  
  class Content(Base):
      __tablename__ = 'content'
      id = Column(Integer, primary_key=True)
      page_id = Column(Integer, ForeignKey('page.id'))
      html = Column(String, unique=True)
      page = relationship(Page)
  
  
  engine = create_engine('sqlite:///web.db')
  Base.metadata.create_all(engine)
  