code: func NewFileSource() FileSource {
  	if fileConfigSource == nil {
  		fileConfigSource = new(fileSource)
  		fileConfigSource.priority = fileSourcePriority
  		fileConfigSource.files = make([]file, 0)
  		fileConfigSource.fileHandlers = make(map[string]FileHandler)
  	}
  
  	return fileConfigSource
  }
docs: //NewFileSource creates a source which can handler local files