e-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>Folds over all cells under a variable and field path. A field path is &quot;terminal&quot; if its length (that includes the prefixed fields given as parameters) is equal to <a href="../../../IBase/Config/index.html#val-lineage_field_depth"><code>IBase.Config.lineage_field_depth</code></a>, or no more field can be subscripted from its corresponding type, 