title: RegEx for matching mp3 URLs
body: <p>How can I get an mp3 url with REGEX?</p>
  
  <p>This mp3 url, for example: </p>
  
  <pre>
  https://www.soundhelix.com/examples/mp3/SoundHelix-Song-1.mp3
  </pre>
  
  <p>This is a what I've tried so far but I want it to only accept a url with '.mp3' on the end.</p>
  
  <pre><code>(https?|ftp|file)://[-a-zA-Z0-9+&amp;@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&amp;@#/%=~_|]
  </code></pre>