Control log output and capture events for testing:

```vary
import log

log.set_level("DEBUG")
log.set_sink("stderr")

# Capture log events for testing
log.capture()
# ... code that logs ...
let events = log.events()
```

| **Function** | **Returns** | **Description** |
|----------|---------|-------------|
| `log.set_level(level)` | `None` | Set log level: `"DEBUG"`, `"INFO"`, `"WARN"`, `"ERROR"` |
| `log.set_sink(sink)` | `None` | Set sink: `"stdout"`, `"stderr"`, or a file path |
| `log.capture()` | `None` | Start capturing log events |
| `log.events()` | `List[Str]` | Stop capturing and return captured events |