basic_router attempts to emulate the Express JS router, while translating its behaviors into idiomatic C++. for example, in the C++ model the response object is fully set up and returned to the framework for sending, unlike Express where res.send() actually sends the body using Node's cooperative I/O model. Greatly expand and elaborate the documentation in include/boost/beast2/server/basic_router.hpp by inspecting the headers and sources to deeply understand how the class works. Use Express JS router as a guide but verify any claims. Use examples liberally.