code: func (t *NetworkTarget) Open(errWriter io.Writer) error {
  	t.Filter.Init()
  
  	if t.BufferSize < 0 {
  		return errors.New("NetworkTarget.BufferSize must be no less than 0")
  	}
  	if t.Network == "" {
  		return errors.New("NetworkTarget.Network must be specified")
  	}
  	if t.Address == "" {
  		return errors.New("NetworkTarget.Address must be specified")
  	}
  
  	t.entries = make(chan *Entry, t.BufferSize)
  	t.conn = nil
  
  	if t.Persistent {
  		if err := t.connect(); err != nil {
  			return err
  		}
  	}
  
  	go t.sendMessages(errWriter)
  
  	return nil
  }
docs: // Open prepares NetworkTarget for processing log messages.