">for</span> <span class="n">x</span> <span class="ow">in</span> <span class="n">transaction</span><span class="p">]</span>
                <span class="n">key</span> <span class="o">=</span> <span class="p">[</span><span class="n">x</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="k">for</span> <span class="n">x</span> <span class="ow">in</span> <span class="n">transaction</span><span class="p">]</span>
                
                <span class="n">fs</span> <