class Tray {
    constructor(prods) {
        this.products = prods || [];
    }

    add(prod) {
        this.products.push(prod);
    }

    calculate(){
        let sum = 0;
        /**
         * Calculate the sum of all products
         * in the tray and pass it back. Do
         * not change the code given
         */
        return sum;
    }
}
