These APIs can be quite important for certain types of servers.
I started trying to implement it and then realised how tricky it is to correctly support flags.
      def close_write
        stop
      end
      def shutdown(flags)
        if flags == ???
        stop
        to_io.shutdown(flags)
      end
 
Since the flags can be a symbol, a string, etc.
Also, I don't think SSLSocket can support close_read but I'll experiment.