[C++] Implementing +=
diff --git a/value.h b/value.h
index 0236b42..3b3e324 100644
--- a/value.h
+++ b/value.h
@@ -38,4 +38,8 @@
 
 string JoinValues(const vector<Value*> vals, const char* sep);
 
+Value* NewExpr3(Value* v1, Value* v2, Value* v3);
+
+Value* NewLiteral(const char* s);
+
 #endif  // VALUE_H_