title: How to sort an array in descending order?
body: <p>I have an array:</p>
  
  <pre><code>a = [ 0,9,6,12,1]
  </code></pre>
  
  <p>I need a way to sort it in descending order:</p>
  
  <pre><code>a = [12,9,6,1,0]
  </code></pre>
  
  <p>For sorting in ascending order I have a Ruby function <code>a[].to_a.sort</code>,
  I'm looking for a function to sort the array in descending order.</p>