def step_three
      redirect_to '/checkout/step-one' and return if !logged_in?
      redirect_to '/checkout/step-two' and return if @order.shipping_address.nil? || @order.billing_address.nil?
      @rates = ShippingCalculator.rates(@order)
      @selected_rate = ShippingCalculator.rate(@order)
    end
def step_three
      redirect_to '/checkout/step-one' and return if !logged_in?
      redirect_to '/checkout/step-two' and return if @order.shipping_address.nil? || @order.billing_address.nil?
      @rates = ShippingCalculator.rates(@order)
      @selected_rate = ShippingCalculator.rate(@order)
    end
GET /checkout/step-three