nd&nbsp;:&nbsp;<span class="keywordsign">'</span>a&nbsp;array&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="keywordsign">'</span>a&nbsp;array&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="keywordsign">'</span>a&nbsp;array<br>
&nbsp;&nbsp;<span class="keyword">val</span>&nbsp;concat&nbsp;:&nbsp;<span class="keywordsign">'</span>a&nbsp;array&nbsp;list&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;<span class="keywordsign">'</span>a&nbsp;array<br>
&nbsp;&nbsp;<span class="key