code: func PemCert(privKey *rsa.PrivateKey, domain string, expiration time.Time) ([]byte, error) {
  	derBytes, err := derCert(privKey, expiration, domain)
  	if err != nil {
  		return nil, err
  	}
  
  	return pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: derBytes}), nil
  }
docs: // PemCert generates PEM cert file