code: func (whisper *Whisper) Envelopes() []*Envelope {
  	whisper.poolMu.RLock()
  	defer whisper.poolMu.RUnlock()
  
  	all := make([]*Envelope, 0, len(whisper.envelopes))
  	for _, envelope := range whisper.envelopes {
  		all = append(all, envelope)
  	}
  	return all
  }
docs: // Envelopes retrieves all the messages currently pooled by the node.