lua下面dump出一个table的结构

--- @brief 调试时打印变量的值--- @param data 要打印的字符串--- @param [max_level] table要展开打印的计数，默认nil表示全部展开--- @param [prefix] 用于在递归时传递缩进，该参数不供用户使用于--- @ref http://dearymz.blog.163.com/blog/static/205657420089251655186/function var_dump(data, max_level, prefix)    if type(prefix) ~= "string" then        prefix = ""    end    if type(data) ~= "table" then        print(prefix .. tostring(data))    else        print(data)        if max_level ~= 0 then            local prefix_next = prefix .. "    "            print(prefix .. "{")            for k,v in pairs(data) do                io.stdout:write(prefix_next .. k .. " = ")                if type(v) ~= "table" or (type(max_level) == "number" and max_level <= 1) then                    print(v)                else                    if max_level == nil then                        var_dump(v, nil, prefix_next)                    else                        var_dump(v, max_level - 1, prefix_next)                    end                end            end            print(prefix .. "}")        end    endendfunction vd(data, max_level)    var_dump(data, max_level or 5)end