Estoy tratando de entender qué está pasando y por qué defineConstraints no es una función. alguien me puede ayudar ?

Heres ejemplos de mi código.

índice.js

 const Sequelize = require('sequelize'); config = require('config'); const dbConf = config.get('database'); console.log(dbConf); const sequelize = new Sequelize(dbConf.database, dbConf.user, dbConf.password,{ dialect: 'postgres', host: dbConf.host, port: dbConf.port, logging: console.log }); sequelize.Model = Sequelize.Model; const models = { User: sequelize.import(__dirname + '/models/user.js'), Service: sequelize.import (__dirname + '/models/service.js'), Subscriber: sequelize.import (__dirname + '/models/subscriber.js'), }; for(const model in models) { models[model].defineConstraints(models); } models.Op = Sequelize.Op; models.sequelize = sequelize; module.exports = models;