Saving mergedStream.pipe(process.stdout) as file

[JonthMM]

Hello and thank you for providing this workful tool!

Everything works fine when I use mergeFeatureCollectionStream as following:

var mergedStream = geojsonMerge.mergeFeatureCollectionStream([
    './public/uploads/usertrainingspolygonegjson.geojson',
    './public/uploads/digitalized_usertrainingspolygons.geojson'])

    mergedStream.pipe(process.stdout);

But my problem now is, that it only prints the combined geojson as text in my console and my question would be if there is any way to save the output to a geojson file?

Best regards and thank you very much!