lua 代码有什么问题？

local consumer = coroutine.create(function(i)
   while true do
    i = i - 1
    print('consumer: ' .. i)
    coroutine.yield(i)
   end
end)

local producer = coroutine.create(function()
   while true do
     i = i or 0
     i = i + 1
     print('producer: ' .. i)
     status, value = coroutine.resume(consumer, i)
     i = value
   end
end)

coroutine.resume(producer)

但实际结果完全不同，正确的输出应该是： 0 1 0 1 01