code: func NewParser(fs afero.Fs) *Parser {
  	if fs == nil {
  		fs = afero.OsFs{}
  	}
  
  	return &Parser{
  		fs: afero.Afero{Fs: fs},
  		p:  hclparse.NewParser(),
  	}
  }
docs: // NewParser creates and returns a new Parser that reads files from the given
  // filesystem. If a nil filesystem is passed then the system's "real" filesystem
  // will be used, via afero.OsFs.