数据结构格式(YAML或whatnot)保留注释的往返解析，用于编写配置。

I have been using YAML as configuration file format in several applications, and all went well except one thing: when my program needs to write/modify a config variable in a YAML config file, it destroys formatting and comments by loading and dumping the entire file/structure.I have been using YAML as configuration file fo