code: func (whisper *Whisper) LightClientMode() bool {
  	val, exist := whisper.settings.Load(lightClientModeIdx)
  	if !exist || val == nil {
  		return false
  	}
  	v, ok := val.(bool)
  	return v && ok
  }
docs: //LightClientMode indicates is this node is light client (does not forward any messages)