Actions after download is completed

Where do i process the downloaded file after download action is completed?
For examples, if I download a .zip file, I'd want to write a function to extract the file right away. Where can I put the extract function?
I tried to put function extract() in _bindBackgroundIsolate() and it worked, but only when I'm at the widget that contains _bindBackgroundIsolate(). If I'm at another widget, function extract() doesn't run at all

Edit: to be exact, i put function extract() inside port.listen to get the complete event. But as far as I know, port is define as a ReceivePort, and it is not a broadcast stream, so calling port.listen from another widget will not work

Start by reading the plugin's _bindBackgroundIsolate implementation and the ReceivePort port.listen handling described in the issue. Trace how download-completion events are delivered when the listening widget is not mounted. Done means the issue has a defined, reliable place for post-download processing such as extracting a completed .zip file, with the behavior clarified for the affected Flutter platforms.

Written by the indexing model from the issue text.