# File lib/gettext_i18n_rails/ruby_gettext_extractor.rb, line 87
    def extract_key(args, seperator)
      key = nil
      if args.size == 2
        key = extract_string(args.value)
      else
        # this could be n_("aaa","aaa2",1)
        # all strings arguemnts are extracted and joined with \004 or \000

        arguments = args[1..(-1)]

        res = []
        arguments.each do |a|
          str = extract_string(a)
          # only add strings
          res << str if str
        end

        return nil if res.empty?
        key = res.join(seperator)
      end

      return nil unless key

      key.gsub!("\n", '\n')
      key.gsub!("\t", '\t')
      key.gsub!("\0", '\0')

      return key
    end