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: feed.rb
    path of file: ./repos/artichoke/artichoke-backend/src/extn/stdlib/vendor/gen/rss/maker
    
    the code of the file until where you have to start completion: # frozen_string_literal: false
require_relative "atom"

module RSS
  module Maker
    module Atom
      class Feed < RSSBase
        def initialize(feed_version="1.0")
          super
          @feed_type = "atom"
          @feed_subtype = "
    
            def to_feed(feed)
              set_default_values do
                entry = feed.class::Entry.new
                set = setup_values(entry)
                entry.dc_dates.clear
                setup_other_elements(feed, entry)
                if set
                  feed.entries << entry
                  set_parent(entry, feed)
                elsif variable_is_set?
                  raise NotSetError.new("maker.item", not_set_required_variables)
                end
              end