class="num">2</span>,<span class="lit">'b'</span>))</pre><p>whereas</p><pre>Index[(<span class="std">Char</span>, <span class="std">Int</span>)]((<span class="lit">'x'</span>,<span class="num">1</span>), (<span class="lit">'y'</span>,<span class="num">2</span>)) stack Index[<span class="std">Char</span>](<span class="lit">'a'</span>,<span class="lit">'b'</span>)</pre><p>results in</p><pre>Index[(<span class="std">Char</span>, <span class="std">Int</span>, <span class="std">Char</span>)]((<span class="lit">'