Prolog: add introduction for the sets group and make it visible

1 files changed, 11 insertions, 0 deletions

diff --git a/prolog/problems/sets/count_3/en.py b/prolog/problems/sets/count_3/en.py
new file mode 100644
index 0000000..481fd1c
--- /dev/null
+++ b/prolog/problems/sets/count_3/en.py
@@ -0,0 +1,11 @@
+name = 'count/3'
+slug = 'find the number of occurrences of an element in list'
+
+description = '''\
+<p><code>count(X, L, N)</code>: <code>N</code> is the number of times the element <code>X</code> appears in the list <code>L</code>.</p>
+<pre>
+?- count(1, [1,2,1,3,1], N).
+  N = 3.
+</pre>'''
+
+hint = {}