d among <code class="code">2^{30}</code> different hash functions.
   All these hash functions have different collision patterns,
   rendering ineffective the denial-of-service attack described above.
   However, because of randomization, enumerating all elements of the
   hash table using <a href="Hashtbl.html#VALfold"><code class="code"><span class="constructor">Hashtbl</span>.fold</code></a> or <a href="Hashtbl.html#VALiter"><code class="code"><span class="constructor">Hashtbl</span>.iter</code></a> is n