code: func GetLocalRootCA(paths CertPaths) (RootCA, error) {
  	// Check if we have a Certificate file
  	cert, err := ioutil.ReadFile(paths.Cert)
  	if err != nil {
  		if os.IsNotExist(err) {
  			err = ErrNoLocalRootCA
  		}
  
  		return RootCA{}, err
  	}
  	signingCert := cert
  
  	key, err := ioutil.ReadFile(paths.Key)
  	if err != nil {
  		if !os.IsNotExist(err) {
  			return RootCA{}, err
  		}
  		// There may not be a local key. It's okay to pass in a nil
  		// key. We'll get a root CA without a signer.
  		key = nil
  		signingCert = nil
  	}
  
  	return NewRootCA(cert, signingCert, key, DefaultNodeCertExpiration, nil)
  }
docs: // GetLocalRootCA validates if the contents of the file are a valid self-signed
  // CA certificate, and returns the PEM-encoded Certificate if so