_result</a></span></code></dt></dl><aside><p>A validator takes an input an returns a validator result</p></aside><dl><dt class="spec type" id="type-validator_builder"><a href="#type-validator_builder" class="anchor"></a><code><span class="keyword">type</span> <span>('input, 'output, 'err) validator_builder</span></code><code> = <span class="type-var">'err</span> <span>&#45;&gt;</span> <span><span>(<span class="type-var">'input</span>, <span class="type-var">'output</span>, <span class="type-var">'err</spa