"code">v</code> or other values to register other
   functions or even itself.  It can raise an exception; in this case
   the exception will interrupt whatever the program was doing when
   the function was called.
<p>

   <code class="code">finalise</code> will raise <code class="code"><span class="constructor">Invalid_argument</span></code> if <code class="code">v</code> is not
   guaranteed to be heap-allocated.  Some examples of values that are not
   heap-allocated are integers, constant constructors,