how to trigger a method after a background upload is finished ?

I need my application to encrypt a text file and save it to local storage after downloading it using the flutter uploader .
so how can I use my dart function that encrypts and save files?

The issue mentions no files, tests, or entry points. First clarify which completion event or callback is available in flutter_uploader and the expected encryption and local-storage behavior; done should include a reproducible way to run the Dart function after the download finishes.

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