punctuation">]</span><span class="operator">:</span> <span class="builtin">string</span> <span class="operator">|</span> <span class="type"><a href="/api/ui-react-dom/type-aliases/configuration/customcell/">CustomCell</a></span><span class="punctuation">}</span><span class="punctuation">;</span>
  extraCellsBefore<span class="operator">?</span><span class="operator">:</span> <span class="type"><a href="/api/ui-react-dom/type-aliases/configuration/extrarowcell/">ExtraRowCell</a></span><span class="punctuatio