diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3d06c33..42d3f2b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@
 cmake_minimum_required(VERSION 3.15.2)
 project(python_interpreter)
 set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Ofast")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g")
 
 include_directories(/usr/include/antlr4-runtime/)
 include_directories(
diff --git a/src/Evalvisitor.cpp b/src/Evalvisitor.cpp
index 5abbeeb..195bd88 100644
--- a/src/Evalvisitor.cpp
+++ b/src/Evalvisitor.cpp
@@ -176,9 +176,13 @@ std::any EvalVisitor::visitContinue_stmt(
 }
 
 std::any EvalVisitor::visitReturn_stmt(Python3Parser::Return_stmtContext *ctx) {
-  // TODO
-  throw FatalError("Not implemented in function visitReturn_stmt");
-  return visitChildren(ctx);
+  if (!ctx->testlist()) return FlowType(RETURN, std::vector<std::any>());
+  std::any val = visitTestlist(ctx->testlist());
+  std::vector<std::any> *val_ptr = std::any_cast<std::vector<std::any>>(&val);
+  if (val_ptr) return FlowType(RETURN, *val_ptr);
+  std::vector<std::any> tmp;
+  tmp.push_back(val);
+  return FlowType(RETURN, tmp);
 }
 
 std::any EvalVisitor::visitCompound_stmt(
@@ -332,15 +336,15 @@ std::any EvalVisitor::visitFactor(Python3Parser::FactorContext *ctx) {
 std::any EvalVisitor::visitAtom_expr(Python3Parser::Atom_exprContext *ctx) {
   if (!ctx->trailer()) {
     auto val = visitAtom(ctx->atom());
-    std::cerr << "[Log] In func visitAtom_expr. The Atom returns : ";
-    if (auto ptr = std::any_cast<NoneType>(&val)) {
-      std::cerr << "NoneType" << std::endl;
-    } else if (auto ptr = std::any_cast<RawVarible>(&val)) {
-      std::cerr << "Variable Name=" << ptr->name
-                << " val=" << Any2String(Variables.ReadVariable(ptr->name))
-                << std::endl;
-    } else
-      std::cerr << Any2String(val) << std::endl;
+    // std::cerr << "[Log] In func visitAtom_expr. The Atom returns : ";
+    // if (auto ptr = std::any_cast<NoneType>(&val)) {
+    //   std::cerr << "NoneType" << std::endl;
+    // } else if (auto ptr = std::any_cast<RawVarible>(&val)) {
+    //   std::cerr << "Variable Name=" << ptr->name
+    //             << " val=" << Any2String(Variables.ReadVariable(ptr->name))
+    //             << std::endl;
+    // } else
+    //   std::cerr << Any2String(val) << std::endl;
     return val;
   }
   std::string func_name = ctx->atom()->NAME()->getText();
diff --git a/src/names.cpp b/src/names.cpp
index 06c1210..cfea34f 100644
--- a/src/names.cpp
+++ b/src/names.cpp
@@ -52,7 +52,7 @@ std::any FucntionContainer::CallFunction(
   if (name == "print") {
     bool is_first = true;
     for (int i = 0; i < args.size(); i++) {
-      if (is_first) std::cout << ' ';
+      if (!is_first) std::cout << ' ';
       is_first = false;
       std::string buf = Any2String(args[i].value);
       std::cout << buf;
@@ -125,10 +125,13 @@ std::any FucntionContainer::CallFunction(
   std::any res = vis.visit(func.code_address);
   Variables.DestroyFrame();
   FlowType *flow = std::any_cast<FlowType>(&res);
-  if(!flow)
-  {
-    if(flow->ReturnValueLists.size()==1) return flow->ReturnValueLists[0];
-    else return flow->ReturnValueLists;
+  if (!flow) {
+    if (flow->ReturnValueLists.size() == 0)
+      return NoneType();
+    else if (flow->ReturnValueLists.size() == 1)
+      return flow->ReturnValueLists[0];
+    else
+      return flow->ReturnValueLists;
   }
   return NoneType();
 }
\ No newline at end of file
diff --git a/src/utils.cpp b/src/utils.cpp
index 3ec51d1..7b1a776 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -61,9 +61,11 @@ std::string Any2String(const std::any &value) {
     buf << *ptr;
   else if (auto ptr = std::any_cast<std::string>(&value))
     buf << *ptr;
+  else if (auto ptr = std::any_cast<NoneType>(&value))
+    buf << "None";
   else
     throw FatalError("Any2String: unknown type");
-  buf >> res;
+  std::getline(buf, res);
   return res;
 }