code: func (whisper *Whisper) MinPow() float64 {
  	val, exist := whisper.settings.Load(minPowIdx)
  	if !exist || val == nil {
  		return DefaultMinimumPoW
  	}
  	v, ok := val.(float64)
  	if !ok {
  		log.Error("Error loading minPowIdx, using default")
  		return DefaultMinimumPoW
  	}
  	return v
  }
docs: // MinPow returns the PoW value required by this node.