title: Understanding statement in a yaml file env-supported: ${ENV|dev=true:false}
body: <p>As part of our ci/cd, we have a config file like</p>
  <pre><code>name: ${CDSENV}-volume-action
  type: function
  region: ${LAMBDA_REGION:${REGION}}
  env-supported: ${ENV|dev=true:false}
  ...
  </code></pre>
  <p>The final line of this is confusing me... <code>${ENV|dev=true:false}</code></p>
  <p>I know that this evaluates to <code>true</code> if ENV is 'dev', and false otherwise, but I can't find what this type of statement is called, and I get an error when I try and run it in my terminal.   I cant find documentation on any kind of parameter expansion that relies on a | as an evaluator.</p>
  <p>Any help is appreciated.</p>