name = 'len/2'
slug = 'find the length of a list'

description = '''\
<p><code>len(L, Len)</code>: <code>Len</code> is the length of the list <code>L</code>.</p>
<pre>
?- len([1,2,3], Len).
  Len = 3.
</pre>'''

hint = {}