code: func CouldBeScript(info os.FileInfo) ScriptConfidence {
  	name := info.Name()
  	switch {
  	case info.IsDir(), name[0] == '.':
  		return ConfNotScript
  	case info.Mode()&os.ModeSymlink != 0:
  		return ConfNotScript
  	case extRe.MatchString(name):
  		return ConfIsScript
  	case strings.IndexByte(name, '.') > 0:
  		return ConfNotScript // different extension
  	case info.Size() < int64(len("#/bin/sh\n")):
  		return ConfNotScript // cannot possibly hold valid shebang
  	default:
  		return ConfIfShebang
  	}
  }
docs: // CouldBeScript reports how likely a file is to be a shell script. It
  // discards directories, symlinks, hidden files and files with non-shell
  // extensions.