n>converter<span class="hl opt">.</span><span class="hl kwd">document</span><span class="hl opt">(</span>window<span class="hl opt">.</span>document<span class="hl opt">,</span> output<span class="hl opt">);</span>
        <span class="hl kwa">if</span> <span class="hl opt">(</span>cb <span class="hl opt">!=</span> <span class="hl kwa">null</span><span class="hl opt">) {</span>
          <span class="hl kwa">return</span> <span class="hl kwd">cb</span><span class="hl opt">(</span><span class="hl kwa">null</