text: from app import db, login_manager
  from werkzeug.security import generate_password_hash, check_password_hash
  from flask_login import UserMixin
  
  class User(UserMixin, db.Model):
      id = db.Column(db.Integer, primary_key=True)
      username = db.Column(db.String(64), index=True, unique=True)
      email = db.Column(db.String(120), unique=True, index=True) 
      password_hash = db.Column(db.String(128))
  
      def set_password(self, password):
          self.password_hash = generate_password_hash(password)
  
      def check_password(self, password):
          return check_password_hash(self.password_hash, password)
  
      def __repr__(self):
          return '<User %r' % self.username
  
  @login_manager.user_loader
  def load_user(id):
      return User.query.get(int(id))