You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: xor.go
    path of file: ./repos/vault/sdk/helper/xor
    
    the code of the file until where you have to start completion: // Copyright (c) HashiCorp, Inc.
// SPDX-Licen
    
func XORBase64(a, b string) ([]byte, error) {
	aBytes, err := base64.StdEncoding.DecodeString(a)
	if err != nil {
		return nil, fmt.Errorf("error decoding first base64 value: %w", err)
	}
	if aBytes == nil || len(aBytes) == 0 {
		return nil, fmt.Errorf("decoded first base64 value is nil or empty")
	}

	bBytes, err := base64.StdEncoding.DecodeString(b)
	if err != nil {
		return nil, fmt.Errorf("error decoding second base64 value: %w", err)
	}
	if bBytes == nil || len(bBytes) == 0 {
		return nil, fmt.Errorf("decoded second base64 value is nil or empty")
	}

	return XORBytes(aBytes, bBytes)
}