Convert shopify shipping script to shopify function to select shipping rate

Retired Boards Appdev Functions
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1

hi i am wondering does the shopify function supports the following?

class CustomizedShipping
  DISCOUNT_PREFIX = 'PRE'
  
  def self.run(shipping_rates, cart)
    cheapest_shipping_rate = shipping_rates.sort_by!(&:price).first
    cart_discount = cart.discount_code
    
    return unless cart_discount
    return unless cheapest_shipping_rate
    return unless cart_discount.code.start_with?(CustomizedShipping::DISCOUNT_PREFIX)
    
    shipping_rates.each do |shipping_rate|
      if shipping_rate.code == cheapest_shipping_rate.code
        shipping_rate.apply_discount(shipping_rate.price * 1.0, message: "Free Shipping")
      end
    end
  end
end

CustomizedShipping.run(Input.shipping_rates, Input.cart) 
Output.shipping_rates = Input.shipping_rates

if so which graphql query should i use to fetch shipping_rates? it seems that the shipping rate is from

CalculatedDraftOrder

and when i use

  [[extensions.targeting]]
  target = "purchase.shipping-discount.run"
  input_query = "src/run.graphql"
  export = "run"

i didn’t see CalculatedDraftOrder node inside the generated code