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: parser.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 "forwardable"
require "open-uri"

require_relative "rss"
require_relative "xml"

module RSS

 
    
    def check_ns(tag_name, prefix, ns, require_uri, ignore_unknown_element=nil)
      if _ns(ns, prefix) == require_uri
        true
      else
        if ignore_unknown_element.nil?
          ignore_unknown_element = @ignore_unknown_element
        end