code: func GenerateRSAPrivateKeyPEM() ([]byte, error) {
  	priv, err := rsa.GenerateKey(rand.Reader, teleport.RSAKeySize)
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	return pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)}), nil
  }
docs: // GenerateRSAPrivateKeyPEM generates new RSA private key and returns PEM encoded bytes