entry.go
func (e *Entry) execPrefix(method, urlStr string) (*Route, []string) {
	if !strings.HasPrefix(urlStr, e.pattern) {
		return nil, nil
	}
	if len(urlStr) == len(e.pattern) {
		return e.GetHandler(method), nil
	}
	return e.traverse(method, urlStr[len(e.pattern):])
}
func (e *Entry) execPrefix(method, urlStr string) (*Route, []string) {
	if !strings.HasPrefix(urlStr, e.pattern) {
		return nil, nil
	}
	if len(urlStr) == len(e.pattern) {
		return e.GetHandler(method), nil
	}
	return e.traverse(method, urlStr[len(e.pattern):])
}
// execPrefix simply see if the given urlStr has a leading pattern.