entry.go
func (e *Entry) SetHandler(h *Route) error {
	if e.handler != nil {
		return errors.New("Duplicate Route registration")
	}
	e.handler = h
	return nil
}
func (e *Entry) SetHandler(h *Route) error {
	if e.handler != nil {
		return errors.New("Duplicate Route registration")
	}
	e.handler = h
	return nil
}
// SetHandler reigsters the given handler that matches with any method.