>entries</var> be the List that is <var>set</var>.<var class="field">[[SetData]]</var>.</li><li>Let <var>accumulator</var> be <emu-val>undefined</emu-val></li><li>Let <var>first</var> be <emu-val>true</emu-val>.</li><li>If <var>initialValue</var> is present, then<ol><li>Set <var>accumulator</var> to <var>initialValue</var></li></ol></li><li>For each <var>e</var> that is an element of <var>entries</var>, in original insertion order, do:<ol><li>If <var>e</var> is not <code>empty</code>, then<ol><li>If <var>fi