# File lib/sass/scss/parser.rb, line 1170
      def tok(rx, last_group_lookahead = false)
        res = @scanner.scan(rx)
        if 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
      end