diff --git a/SyntaxTree/tree/BaseEnterExitVisitor.cs b/SyntaxTree/tree/BaseEnterExitVisitor.cs
new file mode 100644
index 000000000..123d5e9c5
--- /dev/null
+++ b/SyntaxTree/tree/BaseEnterExitVisitor.cs
@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using PascalABCCompiler;
+using PascalABCCompiler.SyntaxTree;
+
+namespace PascalABCCompiler.SyntaxTree
+{
+    public class BaseEnterExitVisitor: WalkingVisitorNew
+    {
+        public BaseEnterExitVisitor()
+        {
+            OnEnter = Enter;
+            OnLeave = Exit;
+        }
+
+        public virtual void Enter(syntax_tree_node st)
+        {
+        }
+        public virtual void Exit(syntax_tree_node st)
+        {
+        }
+    }
+}
diff --git a/_ParsePABC1/ParsePABC1/ProcessYieldsCapturedVars.cs b/_ParsePABC1/ParsePABC1/ProcessYieldsCapturedVars.cs
index 83dcb65ea..c37864255 100644
--- a/_ParsePABC1/ParsePABC1/ProcessYieldsCapturedVars.cs
+++ b/_ParsePABC1/ParsePABC1/ProcessYieldsCapturedVars.cs
@@ -54,7 +54,8 @@ namespace ParsePABC1
             foreach (var m in fields)
                 cm.Add(m);
             cm.Add(pd);
-            return new type_declaration(newClassName(), SyntaxTreeBuilder.BuildClassDefinition(cm), SyntaxTreeBuilder.BuildGenSC);
+            var td = new type_declaration(newClassName(), SyntaxTreeBuilder.BuildClassDefinition(cm), SyntaxTreeBuilder.BuildGenSC);
+            return td;
         }
 
         public override void visit(procedure_definition pd)