# File lib/css_parser/parser.rb, line 509
    def circular_reference_check(path)
      path = path.to_s
      if @loaded_uris.include?(path)
        raise CircularReferenceError, "can't load #{path} more than once" if @options[:io_exceptions]
        return false
      else
        @loaded_uris << path
        return true
      end
    end