title: Get a list of variables with a specified prefix
body: <p>Is there a way to get a list of user-defined variables that have a specified prefix? For example:</p>
  
  <pre><code>set(vars_MyVar1 something)
  set(vars_MyVar2 something)
  getListOfVarsStartingWith(vars_)
  </code></pre>
  
  <p>?</p>