pan class="op">(</span></span>
<span>  <span class="va">y</span> <span class="op">~</span> <span class="va">sigma_y</span><span class="op">^</span><span class="fl">2</span></span>
<span><span class="op">)</span></span>
<span></span>
<span><span class="co"># Add vector input</span></span>
<span><span class="va">model</span><span class="op">$</span><span class="fu">addInput</span><span class="op">(</span><span class="va">u</span><span class="op">)</span></span>
<span></span>
<span><span class="co"># Specify p