# File lib/sass/scss/parser.rb, line 1121
      def tok!(rx)
        t = tok(rx)
        return t if t
        name = TOK_NAMES[rx]

        unless name
          # Display basic regexps as plain old strings
          source = rx.source.gsub(%r{\\/}, '/')
          string = rx.source.gsub(/\\(.)/, '\1')
          name = source == Regexp.escape(string) ? string.inspect : rx.inspect
        end

        expected(name)
      end