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# Register tracking state listener (for onStartTracking/onStopTracking events)

```
/**
* Register tracking state listener
*
* @param listener Track state change listener
* @return true if listener registered
*/fun registerCallback(listener: TrackingStateListener): Boolean
```

```
/**
* Unregister tracking state listener
*
* @param listener
* @return true if listener unregistered
*/fun unregisterCallback(listener: TrackingStateListener): Boolean
```