xo-reader: wip: stub for lambda expression

src/reader/lambda_xs.cpp

@@ -0,0 +1,13 @@
+/* @file lambda_xs.cpp */
+
+#include "lambda_xs.hpp"
+
+namespace xo {
+    namespace scm {
+        lambda_xs::lambda_xs() {}
+
+    } /*namespace scm*/
+} /*namespace xo*/
+
+
+/* end lambda_xs.cpp */