# File lib/sass/util.rb, line 243
    def group_by_to_a(enum, &block)
      return enum.group_by(&block).to_a unless ruby1_8?
      order = {}
      arr = []
      enum.group_by do |e|
        res = block[e]
        unless order.include?(res)
          order[res] = order.size
        end
        res
      end.each do |key, vals|
        arr[order[key]] = [key, vals]
      end
      arr
    end