title: How to find out the validity of a URL in Flutter?
body: <p>I don't know of the title is completely appropriate, but here's what I actually want to do. I have urls which point to mp3 files, now some are valid and and some are not, as of now, so before I render the controls for playback of those audio files in my UI, I want to check whether the URL will give me the mp3 or result in a 404. How can I do that?</p>