Coroutine example!

co = coroutine.create(
function()
    for i=1,3 do
        print(i)
        print('status:'..coroutine.status(co))
        coroutine.yield()
    end
end
)

function b()
    coroutine.resume(co)
    return 'status:'..coroutine.status(co)
end

print(b())
print(b())
print(b())