code: func caller() string {
  	pc, file, _, ok := runtime.Caller(2)
  	if ok && filepath.Base(file) == "current.go" {
  		pc, _, _, ok = runtime.Caller(3)
  	}
  	if !ok {
  		return "<unknown>"
  	}
  
  	return runtime.FuncForPC(pc).Name()
  }
docs: // caller returns the name of calling function.