ob&lt;Allocator&gt;` exists (and `Blob` is</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> * a heap-allocating case of it) and plays well with SHM-allocating allocators.  Therefore Default_init_allocator</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> * is less useful.</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><