title: Is there a way to pass a custom file path to warp::fs::file?
body: <p>I'd like to build a custom path, then download a file at that path. Eg,</p>
  <pre class="lang-rust prettyprint-override"><code>        warp::path!(&quot;files&quot; / u32)
              .map(|fileId| {
                  format!(&quot;{}.txt&quot;, *FILES_PATH, fileId)
              })
              .and(warp::fs::file)
  </code></pre>
  <p>But I get an error like:</p>
  <pre><code>the trait bound 'fn(_) -&gt; 
      impl warp::filter::FilterClone {
        warp::filters::fs::file::&lt;_&gt;
      }: warp::filter::FilterBase' is not satisfied
  </code></pre>
  <p>Am I missing an easy way that this can be done?</p>