title: Calculate the duration between now and the next midnight using Chrono
body: <p>What is the idiomatic way to get the duration between now and the next midnight?</p>
  
  <p>I have a function like this:</p>
  
  <pre><code>extern crate chrono;
  
  use chrono::prelude::*;
  use time;
  
  fn duration_until_next_midnight() -&gt; time::Duration {
      let now = Local::now(); // Fri Dec 08 2017 23:00:00 GMT-0300 (-03)
      // ... how to continue??
  }
  </code></pre>
  
  <p>It should make a <code>Duration</code> with 1 hour, since the next midnight is <em>Sat Dec 09 2017 00:00:00 GMT-0300 (-03)</em></p>