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: group.go
    path of file: ./repos/tegola/vendor/github.com/dimfeld/httptreemux
    
    the code of the file until where you have to start completion: package httptreemux

import (
	"fmt"
	"net/url"
	"strings"
)

type Group struct {
	path string
	mux  *TreeMux
}

// Add a sub-group to this group
func (g *Group) NewGroup(path string) *Group {
	if len(path) < 1 {
		panic("Group path must not be empty")
	}

	checkPath(path)
	path = g.path + path
	//Don't want trailing slash as all sub-paths start with slash
	if path[len(path)-1] == '/' {
		path =
    
func (g *Group) Handle(method string, path string, handler HandlerFunc) {
	g.mux.mutex.Lock()
	defer g.mux.mutex.Unlock()

	addSlash := false
	addOne := func(thePath string) {
		node := g.mux.root.addPath(thePath[1:], nil, false)
		if addSlash {
			node.addSlash = true
		}
		node.setHandler(method, handler, false)

		if g.mux.HeadCanUseGet && method == "GET" && node.leafHandler["HEAD"] == nil {
			node.setHandler("HEAD", handler, true)
		}
	}

	checkPath(path)
	path = g.path + path
	if len(path) == 0 {
		panic("Cannot map an empty path")
	}

	if len(path) > 1 && path[len(path)-1] == '/' && g.mux.RedirectTrailingSlash {
		addSlash = true
		path = path[:len(path)-1]
	}

	if g.mux.EscapeAddedRoutes {
		u, err := url.ParseRequestURI(path)
		if err != nil {
			panic("URL parsing error " + err.Error() + " on url " + path)
		}
		escapedPath := unescapeSpecial(u.String())

		if escapedPath != path {
			addOne(escapedPath)
		}
	}

	addOne(path)
}