</a> <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'accum</span>)</span> <span class="arrow">&#45;&gt;</span></span>
  <span>fallback:<span>(<span><span class="type-var">'accum</span> <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'accum</span>)</span> <span class="arrow">&#45;&gt;</span></span>
  <span class="type-var">'accum</span></span></code></div><div class="spec-doc"><p>If a variable path has a shape that corresponds to a statically known set of field labels, 