  90</span><span class="comment">   * Constructs with given payload; also subsumes no-args construction to mean constructing an object with</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment">   * `null() == true`.</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment">   *</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span cla