ing(<a class="reference internal" href="#concat">CONCAT</a> &lt;out-var&gt; [&lt;input&gt;...])
  string(<a class="reference internal" href="#join">JOIN</a> &lt;glue&gt; &lt;out-var&gt; [&lt;input&gt;...])
  string(<a class="reference internal" href="#tolower">TOLOWER</a> &lt;string&gt; &lt;out-var&gt;)
  string(<a class="reference internal" href="#toupper">TOUPPER</a> &lt;string&gt; &lt;out-var&gt;)
  string(<a class="reference internal" href="#length">LENGTH</a> &lt;string&gt; &lt;out-var&gt;)
  string(<a