because all parameters are defined
externally before the block is executed. The transformed parameters
case works even though <code>c</code> isn’t defined at the point it is used,
because constraints on transformed parameters are only validated at
the end of the block. Data variables work like parameter variables,
whereas transformed data and generated quantity variables work like
transformed parameter variables.</p>
</div>
<div id="declaring-optional-variables" class="section level3 unnumbered">
<h3>Decl