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diff --git a/prolog/problems/sets/diff_3/en.py b/prolog/problems/sets/diff_3/en.py
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+++ b/prolog/problems/sets/diff_3/en.py
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+id = 130
+name = 'diff/3'
+slug = 'find the difference of two sets'
+
+description = '''\
+<p><code>diff(S1, S2, D)</code>: the list <code>D</code> contains all elements of <code>S1</code> that don't appear in <code>S2</code>, with no duplicates.</p>
+<pre>
+  ?- diff([2,3,5,1,7,9], [3,7,4,5,6], D).
+    D = [2,1,9].
+</pre>'''
+
+hint = {}