w">&#45;&gt;</span></span> unit)</span> <span class="arrow">&#45;&gt;</span></span>
  <span><span class="optlabel">?format</span>:<span>(<span><span class="xref-unresolved">Stdlib</span>.Format.formatter <span class="arrow">&#45;&gt;</span></span> <span><span class="type-var">'b</span> <span class="arrow">&#45;&gt;</span></span> unit)</span> <span class="arrow">&#45;&gt;</span></span>
  <span><span class="label">read</span>:<span>(<span><span class="type-var">'a</span> <span class="arrow">&#45;&gt;</span></