method tests working again

lib/vool/statement.rb

@@ -36,14 +36,14 @@ module Vool
       raise "Not implemented for #{self}"
     end
 
-    def ct_type
-      nil
-    end
-
   end
 
   class Expression
 
+    def ct_type
+      nil
+    end
+
     def normalize
       raise "should not be normalized #{self}"
     end