:sig
String base64_decode(String raw, bool& ok)

:params
raw : Base64 encoded string
ok : set to `true` when decoding succeeds; set to `false` for invalid input
return value : decoded binary-safe string, or an empty string when decoding fails

:see
>string
base64_encode

:content
Decodes a Base64 string.

Pass a `bool` variable for `ok` so callers can distinguish invalid input from a valid empty decoded value.

Example:

```uce
bool ok = false;
String decoded = base64_decode("aGVsbG8=", ok);
// ok == true
// decoded == "hello"
```

Related:

- PHP: `base64_decode($value, true)`
- JavaScript / Node.js: `Buffer.from(value, "base64")`