code: func ParsePrivateKeyPEM(bytes []byte) (crypto.Signer, error) {
  	block, _ := pem.Decode(bytes)
  	if block == nil {
  		return nil, trace.BadParameter("expected PEM-encoded block")
  	}
  	return ParsePrivateKeyDER(block.Bytes)
  }
docs: // ParsePrivateKeyPEM parses PEM-encoded private key