code: func (s *notificationState) Copy() *notificationState {
  	var stateCopy notificationState
  	stateCopy.notifyBlocks = s.notifyBlocks
  	stateCopy.notifyNewTx = s.notifyNewTx
  	stateCopy.notifyNewTxVerbose = s.notifyNewTxVerbose
  	stateCopy.notifyReceived = make(map[string]struct{})
  	for addr := range s.notifyReceived {
  		stateCopy.notifyReceived[addr] = struct{}{}
  	}
  	stateCopy.notifySpent = make(map[btcjson.OutPoint]struct{})
  	for op := range s.notifySpent {
  		stateCopy.notifySpent[op] = struct{}{}
  	}
  
  	return &stateCopy
  }
docs: // Copy returns a deep copy of the receiver.