">invariants</span><span class="p">:</span> <span class="n">Union</span><span class="p">[</span><span class="n">Generator</span><span class="p">[</span><span class="n">MultipleMomentInvariants</span><span class="p">],</span> <span class="n">List</span><span class="p">[</span><span class="n">MultipleMomentInvariants</span><span class="p">]],</span>
            <span class="n">protein_keys</span><span class="p">:</span> <span class="n">Optional</span><span class="p">[</span><span class="n">List</span><span cl