i = 0
f = Fiber.new do
  loop do
    Fiber.yield i
    i += 1
  end
end

e = Enumerator.produce {f.resume}

p [0, 0, 0, 0].zip e # [[0, 0], [0, 1], [0, 2], [0, 3]]
p [0, 0, 0, 0].zip e # [[0, 5], [0, 6], [0, 7], [0, 8]]

# where does the 4 go?