title: How to refer to a variable within a list in var file in Ansible?
body: <p>I have a variable file that includes a list like below format:</p>
  
  <pre><code>VAR:
    - a: 1
      b: 2
      c: 3
    - a: 4 
      b: 5
      c: 6
  </code></pre>
  
  <p>Here, I want to add another variable referencing a sub variable within a list, for example:</p>
  
  <pre><code>VAR:
    - a: 1
      b: 2
      c: 3
      d: "{{ VAR.0.a }}"
    - a: 4 
      b: 5
      c: 6
      d: "{{ VAR.1.a }}"
  </code></pre>
  
  <p>But they didn't work.</p>
  
  <p>I tried {{ VAR[0].a }} {{ VAR[a] }} {{ VAR.0.a }} and etc,
  but none of them worked.</p>
  
  <p>How do you refer to a sub element within a list?</p>