;</span></span>
  <span><span class="optlabel">?sep</span>:<span><span>(unit, <span class="xref-unresolved">Stdlib</span>.Format.formatter, unit, unit)</span> <span class="xref-unresolved">Stdlib</span>.format4</span> <span class="arrow">&#45;&gt;</span></span>
  <span><span>(<span><span class="xref-unresolved">Stdlib</span>.Format.formatter <span class="arrow">&#45;&gt;</span></span> <span><a href="#type-key">key</a> <span class="arrow">&#45;&gt;</span></span> unit)</span> <span class="arrow">&#45;&gt;</sp