title: Override YAML subkey
body: <p>say I have the following YAML file:</p>
  
  <pre><code>-
     key1: value
  # and so on...
     key99: value
     key100:
        subkey1: value
  # and so on...
        subkey100: value
  -
     key1: value
  # and so on...
     key99: value
     key100:
        subkey1: value
  # and so on...
        subkey100: SOME DIFFERENT VALUE
  </code></pre>
  
  <p>The natural way to handle a large amount of identical data would be with anchors, and overriding just the key that changed.</p>
  
  <p>The question is, here, a subkey is different.  Is there an easy way to just reference that <code>key100['subkey100']</code> changed?  Or do I have to use a series of anchors at each level?</p>
  
  <p>I.e., is there a shorthand for:</p>
  
  <pre><code>- &amp;anchor
     key1: value
  # and so on...
     key99: value
     key100: &amp;subanchor
        subkey1: value
  # and so on...
        subkey100: value
  -
     &lt;&lt;: *anchor
     key100:
        &lt;&lt;: *subanchor
        subkey100: SOME DIFFERENT VALUE
  </code></pre>