Most of SWIG directives for wrappers are generated automatically with `scripts/wrap`. E.g. all header files in `include/btllib` are automatically included without developer intervention. However, some aspects of SWIG need to be manually setup and for that you need to modify either `extra_common.i` file in this directory (features common to all wrapped languages) or `<language>/extra.i` for the language you want to setup features for. These and if needed `meson.build` are the only files you should be modifying in `wrappers/`, the rest is autogenerated.