39;s some</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment">   * scalar leaf thing, like 4 bytes or whatever; but it could be larger -- or even huge (e.g., a Data or List</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment">   * of huge size, because the user mutated it so via a ::Builder).  Oh, and it has to be zeroed, as by calloc().</span></div>
<div class="line"><a id="l