an class="p">(</span><span class="n">_</span> <span class="nv">source1</span><span class="p">:</span> <span class="kt">I1</span><span class="p">,</span> <span class="n">_</span> <span class="nv">source2</span><span class="p">:</span> <span class="kt">I2</span><span class="p">,</span> <span class="n">_</span> <span class="nv">source3</span><span class="p">:</span> <span class="kt">I3</span><span class="p">,</span> <span class="n">_</span> <span class="nv">source4</span><span class="p">:</span> <span class="k