e-var">'a</span> <span class="arrow">&#45;&gt;</span></span>
  <span>f:<span>( <span><a href="#type-key">key</a> <span class="arrow">&#45;&gt;</span></span> <span><span class="type-var">'a</span> <span class="arrow">&#45;&gt;</span></span> <span><a href="#type-value">value</a> <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'a</span> * <a href="#type-value">value</a> )</span> <span class="arrow">&#45;&gt;</span></span>
  <span class="type-var">'a</span> * <a href="#type-t">t</a></span></c