code: func (s *Server) ListenAndServe() error {
  	if s.conf.TLS != nil {
  		return s.httpsrv.ListenAndServeTLS(
  			s.conf.TLS.CertFile, s.conf.TLS.KeyFile)
  	}
  
  	return s.httpsrv.ListenAndServe()
  }
docs: // ListenAndServe starts to listen and to serve requests.