span class="keyword">val</span> fold_field_labels : 
  <span><span><a href="#type-t">t</a> option</span> <span class="arrow">&#45;&gt;</span></span>
  <span><a href="../VarPath/index.html#type-t">VarPath.t</a> <span class="arrow">&#45;&gt;</span></span>
  <span><span class="label">init</span>:<span class="type-var">'accum</span> <span class="arrow">&#45;&gt;</span></span>
  <span><span class="label">f</span>:<span>(<span><span class="type-var">'accum</span> <span class="arrow">&#45;&gt;</span></span> <span>