title: Struggling with simple reverse function
body: <p>I want to reverse the middle of a list:</p>
  
  <pre><code>ls = [1,2,3,4,5,6,7,8,9,10]
  
  [1,2,3,7,6,5,4,8,9,10]
  </code></pre>
  
  <p>As you can see, three elements [1,2,3] aren't reversed at the beginning, and neither are three elements at the end [8,9,10].</p>
  
  <p>But I just cannot think how to do it with "elegance." I tried a lot of combinations such as:</p>
  
  <pre><code>ls2 = ls[:4] + ls[::-1] + ls[:-4]
  </code></pre>
  
  <p>but I'm getting duplicates. Any help would be appreciated!</p>