Lua队列问题

今天看到Lua程序设计第11章了，表示按照书中的例子打出来，但是不知道正确写用：

List = {}
function List.new ()
    return {first = 0, last = -1}
end

function List.pushleft (list, value)
    local first = list.first - 1
    list.first = first
    list[first] = value
end

function List.pushright (list, value)
    local last = list.last + 1
    list.last = last
    list[last] = value
end

function List.popleft (list)
    local first = list.first
    if first > list.last then error("list is empty") end
    local value = list[first]
    list[first] = nil    -- to allow garbage collection
    list.first = first + 1
    return value
end

function List.popright (list)
    local last = list.last
    if list.first > last then error("list is empty") end
    local value = list[last]
    list[last] = nil     -- to allow garbage collection
    list.last = last - 1
    return value
end

list = {}
list = List.new
for i=1, 10 do
	List.pushleft(list, i)
end

value = List.popleft(list)
while value do
	print(value)
	value = List.popleft(list)
end

　　先记录下来，但还不知道问谁呐