"op">-</span><span class="fl">1</span></span></span>
<span class="r-in"><span><span class="fu">check_positive</span><span class="op">(</span><span class="va">x</span><span class="op">)</span></span></span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="co"># make `0` acceptable</span></span></span>
<span class="r-in"><span><span class="va">x</span> <span class="op">&lt;-</span> <span class="fl">0</span></span></span>
<span class="r-in"><span><span class="fu">check_positive</sp