_hex : string <span>&#45;&gt;</span> string</code></dt><dt class="spec value" id="val-concat_hashes"><a href="#val-concat_hashes" class="anchor"></a><code><span class="keyword">val </span>concat_hashes : string <span>&#45;&gt;</span> string <span>&#45;&gt;</span> string</code></dt><dt class="spec value" id="val-validate_key"><a href="#val-validate_key" class="anchor"></a><code><span class="keyword">val </span>validate_key : string list <span>&#45;&gt;</span> string list option</code></dt><dt class="spec val