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: syndication.rb
    path of file: ./repos/artichoke/artichoke-backend/src/extn/stdlib/vendor/gen/rss
    
    the code of the file until where you have to start completion: # frozen_string_literal: false
require "rss/1.0"

module RSS
  # The prefix for the Syndication XML namespace.
  SY_PREFIX = 'sy'
  # The URI of the Syndication specification.
  SY_URI = "http://purl.org/rss/1.0/modules/syndication/"

  RDF.install_ns(SY_PREFIX, SY_URI)

  module SyndicationModel

    extend BaseModel

    ELEMENTS = []

    def self.append_features(klass)
      super

      klass.install_must_call_validator(SY_PREFIX, SY_URI)
      klass.module_eval do
        [
          ["updatePeriod"],
       
    
    def self.append_features(klass)
      super

      klass.install_must_call_validator(SY_PREFIX, SY_URI)
      klass.module_eval do
        [
          ["updatePeriod"],
          ["updateFrequency", :positive_integer]
        ].each do |name, type|
          install_text_element(name, SY_URI, "?",
                               "#{SY_PREFIX}_#{name}", type,
                               "#{SY_PREFIX}:#{name}")
        end

        %w(updateBase).each do |name|
          install_date_element(name, SY_URI, "?",
                               "#{SY_PREFIX}_#{name}", 'w3cdtf',
                               "#{SY_PREFIX}:#{name}")
        end
      end

      klass.module_eval(<<-EOC, __FILE__, __LINE__ + 1)
        alias_method(:_sy_updatePeriod=, :sy_updatePeriod=)
        def sy_updatePeriod=(new_value)
          new_value = new_value.strip
          validate_sy_updatePeriod(new_value) if @do_validate
          self._sy_updatePeriod = new_value
        end
      EOC
    end