The lists are made of cons, but you can make arbitrary trees with cons.<p>After looking carefully, the <i>kpos</i> is the result of the function <i>find</i>. In this case it&#x27;s a cons with the row and the column of the king. So the code that runs is more like<p><pre><code>  (define kpos (cons 1 2))
  (- (cdr kpos) 1)
</code></pre>
In this case, for clarity I prefer to use a struct instead of a cons to save the position<p><pre><code>  (struct cell (row col))
  (define kpos (cell 1 2))
  (- (cell-col kpos) 1)</code></pre>