title: How to add a column from a file to another file
body: <p>I have a file with two columns as</p>
  
  <pre><code>1 1
  2 3
  3 4
  </code></pre>
  
  <p>and a file with one column as</p>
  
  <pre><code>6
  7
  9
  </code></pre>
  
  <p>I would like to add the second file in the first one. The output should be:</p>
  
  <pre><code>1 1 6
  2 3 7
  3 4 9
  </code></pre>