use mdesk extension instead of md

samples/output_parse/examples/example2.mdesk

@@ -0,0 +1,20 @@
+@sets a_set : {
+    named_set : {1, 3, 7},
+	{not, named, set},
+	@tag_with_params(p1, p2, p3) { e1, e2, e3 },
+	@tag_with_params(p1, p2, p3) @tag2_with_params(p, pp, ppp) { e1, e2, e3 },
+}
+
+@empty_set empty : {
+}
+
+@tagged_unnamed_set {
+	a_label: {unnamed_set_element}
+}
+
+@showcase_mixed_set_scoping {
+	@symbol_label
+	+: (1 2 3],
+	@symbol_label
+	*: [x y z),
+}