code: func (n *Network) listTLSCACertificates() []string {
  	fileName2Path := make(map[string]string)
  	filepath.Walk(filepath.Join(n.RootDir, "crypto"), func(path string, info os.FileInfo, err error) error {
  		// File starts with "tlsca" and has "-cert.pem" in it
  		if strings.HasPrefix(info.Name(), "tlsca") && strings.Contains(info.Name(), "-cert.pem") {
  			fileName2Path[info.Name()] = path
  		}
  		return nil
  	})
  
  	var tlsCACertificates []string
  	for _, path := range fileName2Path {
  		tlsCACertificates = append(tlsCACertificates, path)
  	}
  	return tlsCACertificates
  }
docs: // listTLSCACertificates returns the paths of all TLS CA certificates in the
  // network, across all organizations.