"p">()]</span>

            <span class="n">ons</span> <span class="o">=</span> <span class="nb">len</span><span class="p">([</span><span class="n">n</span> <span class="k">for</span> <span class="n">n</span> <span class="ow">in</span> <span class="n">neighbor_spec</span> <span class="k">if</span> <span class="n">n</span> <span class="ow">in</span> <span class="p">[</span><span class="s2">&quot;O&quot;</span><span class="p">,</span> <span class="s2">&quot;N&quot;</span><span class="p">,</span> <span class="