[feature request] flatten/unflatten to/from `map[string]string` with safe on

[tigerinus]

Hello,

I am looking for a pkg that allows flattening a nested struct to map[string]string so I can save it to a string based text file or KV store.

I find this pkg is almost there, except that when the value is an array or slice, extra handling is needed for my case.

Please consider adding such support. Thanks!