template/scratch.go
func (s *Scratch) Set(k string, v interface{}) string {
	s.init()

	s.Lock()
	defer s.Unlock()
	s.values[k] = v
	return ""
}
func (s *Scratch) Set(k string, v interface{}) string {
	s.init()

	s.Lock()
	defer s.Unlock()
	s.values[k] = v
	return ""
}
// Set stores the value v at the key k. It will overwrite an existing value
// if present.