# File lib/sass/scss/parser.rb, line 1217
      def tok(rx, last_group_lookahead = false)
        res = @scanner.scan(rx)

        return unless res

        # This fixes https://github.com/nex3/sass/issues/104, which affects
        # Ruby 1.8.7 and REE. This fix is to replace the ?= zero-width
        # positive lookahead operator in the Regexp (which matches without
        # consuming the matched group), with a match that does consume the
        # group, but then rewinds the scanner and removes the group from the
        # end of the matched string. This fix makes the assumption that the
        # matched group will always occur at the end of the match.
        if last_group_lookahead && @scanner[-1]
          @scanner.pos -= @scanner[-1].length
          res.slice!(-@scanner[-1].length..-1)
        end

        newline_count = res.count(NEWLINE)
        if newline_count > 0
          @line += newline_count
          @offset = res[res.rindex(NEWLINE)..-1].size
        else
          @offset += res.size
        end

        @expected = nil
        if !@strs.empty? && rx != COMMENT && rx != SINGLE_LINE_COMMENT
          @strs.each {|s| s << res}
        end
        res
      end