gistfile1.txt

class Iter    
  def initialize(arr)
    @f = Fiber.new do
      while item = arr.shift
        Fiber.yield item
      end
    end
  end
  def next
    @f.resume
  end
end

i = Iter.new [1,2,3,2,1,0]
while item = i.next
  puts item
end