title: Extracting column from DataTable
body: <p>I have scenario like below:</p>
  
  <pre><code>  Scenario: do something interesting
      Given the following users
        | first_name | last_name | address |
        | John       | Doe       | add1    |
        | Jane       | Doe       | add2    |
  </code></pre>
  
  <p>How can I extract list of elements, as example: from <strong>first_name</strong> column.</p>
  
  <p>I've tried to use <strong>cucumber.api.DataTable</strong>, but looks like it uses for other purposes.</p>
  
  <p>I can extract only rows and then manage it as I want.</p>