2 files changed, 15 insertions, 5 deletions
diff --git a/prolog/problems/lists/len_2/common.py b/prolog/problems/lists/len_2/common.py
index 94a05c5..538db56 100644
--- a/prolog/problems/lists/len_2/common.py
+++ b/prolog/problems/lists/len_2/common.py
@@ -25,14 +25,11 @@ test_cases = [
         [{'X': '0'}]),
 ]
 
-def test(program, solved_problems):
-    code = (program + '\n' +
-            server.problems.solutions_for_problems('prolog', solved_problems))
-
+def test(code, aux_code):
     n_correct = 0
     engine_id = None
     try:
-        engine_id, output = prolog.engine.create(code=code, timeout=1.0)
+        engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)
         if engine_id is not None and 'error' not in map(itemgetter(0), output):
             # Engine successfully created, and no syntax error in program.
             for query, answers in test_cases:
diff --git a/prolog/problems/lists/len_2/sl.py b/prolog/problems/lists/len_2/sl.py
new file mode 100644
index 0000000..5b9f05a
--- /dev/null
+++ b/prolog/problems/lists/len_2/sl.py
@@ -0,0 +1,13 @@
+# coding=utf-8
+
+name = 'len/2'
+slug = 'Izračunaj dolžino danega seznama'
+
+description = '''\
+<p><code>len(L, Len)</code>: <code>Len</code> je dolžina seznama <code>L</code>.</p>
+<pre>
+  ?- len([1,2,3], Len).
+    Len = 3.
+</pre>'''
+
+hint = {}