text: // import models
  const Product = require('./Product');
  const Category = require('./Category');
  const Tag = require('./Tag');
  const ProductTag = require('./ProductTag');
  
  Product.belongsTo(Category, { foreignKey: 'category_id' });
  
  Category.hasMany(Product, { foreignKey: 'category_id'});
  
  Product.belongsToMany(Tag, {
    through: ProductTag,
    foreignKey: 'product_id'
  });
  
  Tag.belongsToMany(Product, {
    through: ProductTag,
    foreignKey: 'tag_id'
  });
  
  module.exports = { Product, Category, Tag, ProductTag, };
  