You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: router.go
    path of file: ./repos/zinx/znet
    
    the code of the file until where you have to start completion: package znet

import (
	"strconv"
	"sync"

	"github.com/aceld/zinx/ziface"
)

// BaseRouter is used as the base class when implementing a router.
// Depending on the needs, the methods of this base class can be overridden.
// (实现router时，先嵌入
    
func NewGroup(start, end uint32, router *RouterSlices, Handlers ...ziface.RouterHandler) *GroupRouter {
	g := &GroupRouter{
		start:    start,
		end:      end,
		Handlers: make([]ziface.RouterHandler, 0, len(Handlers)),
		router:   router,
	}
	g.Handlers = append(g.Handlers, Handlers...)
	return g
}