 which refers to *x by-pointer.</span>
   <span class="comment">//</span>
   <span class="comment">// *** Note: ensuring that *x outlives the argument to f() is    ***</span>
   <span class="comment">// *** up to the user! Failure to do so could result in a crash! ***</span>

   <span class="identifier">boost</span><span class="special">::</span><span class="identifier">python</span><span class="special">::</span><span class="identifier">call</span><span class="special">&lt;</span><span class="keyword">void