&#45;&gt;</span> char <span>&#45;&gt;</span> string * string</code></dt><dt class="spec value" id="val-encode"><a href="#val-encode" class="anchor"></a><code><span class="keyword">val</span> encode : string <span>&#45;&gt;</span> string</code></dt><dt class="spec value" id="val-digit_hexa"><a href="#val-digit_hexa" class="anchor"></a><code><span class="keyword">val</span> digit_hexa : char <span>&#45;&gt;</span> int</code></dt><dt class="spec value" id="val-decode"><a href="#val-decode" class="anchor"></a><