That is a great question! For this tutorial, I used a mock function to "upload" the files. In your own app, you would use your own uri endpoint to upload the files to. If I used a real uri to upload my files to, I'd unnecessarily be using resources from a real server.
A real world scenario of a user interface that this tutorial can represent is this page: pexels.com/upload/
You select an image, the thumbnail gets displayed, and when you're ready you hit the "Publish" button.
This tutorial shares the same goal (submit/upload files to a destination), except it teaches how you would show to the user what is happening in between as it finishes uploading each file so that the user is constantly engaged with your app.
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