# File lib/xmlsimple.rb, line 296
  def normalize_option_names(options, known_options)
    return nil if options.nil?
    result = Hash.new
    options.each { |key, value|
      lkey = key.downcase
      lkey.gsub!(/_/, '')
      if !known_options.member?(lkey)
        raise ArgumentError, "Unrecognised option: #{lkey}."
      end
      result[lkey] = value
    }
    result
  end