code: func getTagKey(currentTag, addTag string) string {
  	if currentTag == doNotConsiderTag && addTag == doNotConsiderTag {
  		return doNotConsiderTag
  	} else if currentTag == doNotConsiderTag && addTag != doNotConsiderTag {
  		return addTag
  	} else if currentTag != doNotConsiderTag && addTag == doNotConsiderTag {
  		return currentTag
  	}
  
  	return currentTag + `.` + addTag
  }
docs: // get multi level configuration key