title: YAML anchor as a placeholders in URL string
body: <p>Trying to use anchors in an additive way,
  Following YAML code will not work but can explain what I want it to do</p>
  
  <pre><code>  endpoint:
      data.updates.index.name: &amp;UPDATES-INDEX-NAME "data-updates"
      meta.data.type.name: &amp;DATA-TYPE-NAME "meta-data"
      last.run.type.name: &amp;RUN-TYPE-NAME "lastrun"
      search.ctx: *UPDATES-INDEX-NAME "/" *DATA-TYPE-NAME "/_search"
      search.lastrun: *UPDATES-INDEX-NAME "/" *RUN-TYPE-NAME "/_search"
      update.lastrun: *UPDATES-INDEX-NAME "/" *RUN-TYPE-NAME "/"
  </code></pre>
  
  <p>a1: &amp;anchor1 "hello"
  a2: &amp;anchor2 "moon"
  property: *anchor1 "-" *anchor2</p>
  
  <p>property should yield "hello-moon"
  is it possible at all? tried also using ${} instead of anchors</p>