title: Repeat elements in an array twice
body: <p>Write a method that takes a <code>String[]</code> array and returns a new array with the original array repeated twice.</p>
  
  <p>For example:</p>
  
  <pre><code>repeatArray(new String[]{"a", "b", "c"})
  </code></pre>
  
  <p>Should return a new array with the elements:</p>
  
  <pre><code>["a", "b", "c", "a", "b", "c"]
  </code></pre>