func (cg *ContextGroup) PUT(path string, handler http.HandlerFunc) {
	cg.Handle("PUT", path, handler)
}
PUT is convenience method for handling PUT requests on a context group.
package httptreemux
import (
	"context"
	"net/http"
)
type ContextGroup struct {
	group *Group
}
func (g *Group) UsingContext() *ContextGroup {
	return &ContextGroup{g}
}
func (cg *ContextGroup) NewContextGroup(path string) *ContextGroup {
	return &ContextGroup{cg.group.NewGroup(path)}
}
func (cg *ContextGroup) Handle(method, path string, handler http.HandlerFunc) {
	cg.group.Handle(method, path, func(w http.ResponseWriter, r *http.Request, params map[string]string) {
		if params != nil {
			r = r.WithContext(context.WithValue(r.Context(), ParamsContextKey, params))
		}
		handler(w, r)
	})
}
func (cg *ContextGroup) Handler(method, path string, handler http.Handler) {
	cg.group.Handle(method, path, func(w http.ResponseWriter, r *http.Request, params map[string]string) {
		if params != nil {
			r = r.WithContext(context.WithValue(r.Context(), ParamsContextKey, params))
		}
		handler.ServeHTTP(w, r)
	})
}
func (cg *ContextGroup) GET(path string, handler http.HandlerFunc) {
	cg.Handle("GET", path, handler)
}
func (cg *ContextGroup) POST(path string, handler http.HandlerFunc) {
	cg.Handle("POST", path, handler)
}