You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: shipping.rb
    path of file: ./repos/workarea/core/app/models/workarea
    
    the code of the file until where you have to start completion: module Workarea
  class Shipping
    include ApplicationDocument
    include DiscountIds

    field :order_id, type: String
    field :quantities, type: Hash, default: {}
    field :shipping_total, type: Money, default: 0
    field :tax_total, type
    
    def find_method_options(packages)
      return [] if address.blank? || packages.blank?

      origin = ActiveShipping::Location.new(Workarea.config.shipping_origin)
      response = Workarea.config.gateways.shipping.find_rates(
        origin,
        address.to_active_shipping,
        packages
      )

      response.rates.sort_by(&:price).map do |rate|
        ShippingOption.from_rate_estimate(rate)
      end
    end