title: Roll array, uniform circular shift
body: <p>Given an array:</p>
  
  <p><code>arr = [1, 2, 3, 4, 5]</code></p>
  
  <p>I would like to shift all the elements.</p>
  
  <p><code>shift!(arr, 2) =&gt; [4, 5, 1, 2, 3]</code></p>
  
  <p>In Python, this is accomplished with Numpy using <a href="https://docs.scipy.org/doc/numpy-1.15.1/reference/generated/numpy.roll.html#numpy-roll" rel="nofollow noreferrer"><code>numpy.roll</code></a>. How is this done in Julia?</p>