title: Ansible: Output a variable in vars_prompt
body: <p>Is it possible to include the value of an existing variable in the message output by <code>vars_prompt</code>?</p>
  
  <p>I am looking to do something like this:</p>
  
  <pre><code>- hosts: production
  vars_prompt:
      confirm: "This playbook is configured to act on all $hosts hosts, please confirm"
  </code></pre>
  
  <p>...where the question printed by <code>vars_prompt</code> should be:</p>
  
  <p><code>"This playbook is configured to act on all **production** hosts, please confirm"</code></p>