title: How to generate all permutations of an array in Julia?
body: <p>Given I have some array:</p>
  <pre><code>julia&gt; a = [1, 2, 3]
  3-element Vector{Int64}:
   1
   2
   3
  </code></pre>
  <p>how can I generate all of its permutations? I am happy to write this by hand but would also be interested in a built in function which is performant.</p>