code: func (l *LARS) RegisterCustomHandler(customType interface{}, fn CustomHandlerFunc) {
  
  	if l.customHandlersFuncs == nil {
  		l.customHandlersFuncs = make(customHandlers)
  	}
  
  	t := reflect.TypeOf(customType)
  
  	if _, ok := l.customHandlersFuncs[t]; ok {
  		panic(fmt.Sprint("Custom Type + CustomHandlerFunc already declared: ", t))
  	}
  
  	l.customHandlersFuncs[t] = fn
  }
docs: // RegisterCustomHandler registers a custom handler that gets wrapped by HandlerFunc