t;&quot;&quot;</span>
<span class="sd">    Returns index of argument in members.</span>
<span class="sd">    &quot;&quot;&quot;</span>

    <span class="k">for</span> <span class="n">i</span><span class="p">,</span><span class="n">v</span> <span class="ow">in</span> <span class="nb">enumerate</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
      <span class="k">if</span> <span class="n">member</span><span class="o">.</span><span class="n">is_equiv</span><span class="p">(<