vice attack: the attacker sends input crafted to
   create many collisions in the table, slowing the application down.
</p><p>

   A hash table that is created with <code class="code">~random:<span class="keyword">true</span></code> uses the seeded
   hash function <a href="Hashtbl.html#VALseeded_hash"><code class="code"><span class="constructor">Hashtbl</span>.seeded_hash</code></a> with a seed that is randomly
   chosen at hash table creation time.  In effect, the hash function
   used is randomly selecte