span class="co"># [&lt;Assert condition R expression&gt;: `x &gt; 0`] [x is positive] [`x` value:] [-1] </span>
<span class="co"># [&lt;R call stack&gt;:] </span>
<span class="co"># [&lt;R call 1&gt;: tf_assert(x &gt; 0, \"x is positive\")] </span>
<span class="co"># [&lt;R call 2&gt;: stop_if_negative3(x)] </span>
<span class="co"># [&lt;R call 3&gt;: py_resolve_dots(list(...))] </span>
<span class="co"># [&lt;R call 4&gt;: sess$run(stop_if_negative3(x))] </span>
<span class="co"># [&lt;R call 5&gt;: eval(