added fakulltaet.py and list_length.py

fakultaet.py

@@ -0,0 +1,7 @@
+def fakultaet(n):
+    if n == 0:
+        return 1
+    else:
+        return n * fakultaet(n - 1)
+    
+print(fakultaet(5))

recursion/list_lenght.py

@@ -0,0 +1,9 @@
+def list_length(xs):
+    if xs == []:
+        return 0
+    else:
+        return 1 + list_length(xs[1:])
+
+print(list_length([]))
+print(list_length([42]))
+print(list_length([1, 2, 3]))