title: Interchange every other line with awk
body: <p>If I have the input:</p>
  
  <pre><code>line1
  line2
  line3
  line4
  line5
  line6
  </code></pre>
  
  <p>How can I use <code>awk</code> to print</p>
  
  <pre><code>line2
  line1
  line4
  line3
  line6
  line5
  </code></pre>
  
  <p>I feel like <code>awk</code> is likely the best tool since I would like to do this from a stream, but would bash or anything else be a better way?</p>