">model</span> <span class="op">&lt;-</span> <span class="fu"><a href="measurement.html">measurement</a></span><span class="op">(</span><span class="va">model</span><span class="op">)</span></span></span>
<span class="r-in"><span><span class="va">model</span> <span class="op">&lt;-</span> <span class="fu">add_paths</span><span class="op">(</span><span class="va">model</span>, x <span class="op">=</span><span class="op">~</span> <span class="va">a</span><span class="op">*</span><span class="va">x_1</span> <