Why not consider write a code generation tool for each data structure

[baislsl]

I see lots of redundant code in some structure decode class, like city.go country.go isp.go location.go.

It would be great if we write a code generate tool that generates these type of code using the definition in types.go.

[IncSW]

I had plans to refactor this repository in several months. But feel free to contribute.