diff --git a/OpenAI.Chat.Functions.Samples.pas b/OpenAI.Chat.Functions.Samples.pas
index 2a4665d..fc6ed11 100644
--- a/OpenAI.Chat.Functions.Samples.pas
+++ b/OpenAI.Chat.Functions.Samples.pas
@@ -81,7 +81,7 @@ function TChatFunctionWeather.GetName: string;
 
 function TChatFunctionWeather.GetParameters: string;
 begin
-  Result :=
+  Result := // json scheme
     '{' +
     '  "type": "object",' +
     '  "properties": {' +
diff --git a/OpenAI.Chat.Functions.pas b/OpenAI.Chat.Functions.pas
index c4d86f7..26e5712 100644
--- a/OpenAI.Chat.Functions.pas
+++ b/OpenAI.Chat.Functions.pas
@@ -33,6 +33,9 @@   TChatFunction = class abstract(TInterfacedObject, IChatFunction)
 
 implementation
 
+uses
+  System.SysUtils;
+
 { TChatFunction }
 
 constructor TChatFunction.Create;
@@ -48,9 +51,17 @@ function TChatFunction.Execute(const Args: string): string;
 class function TChatFunction.ToJson(Value: IChatFunction): TJSONObject;
 begin
   Result := TJSONObject.Create;
-  Result.AddPair('name', Value.GetName);
-  Result.AddPair('description', Value.GetDescription);
-  Result.AddPair('parameters', TJSONObject.ParseJSONValue(Value.GetParameters));
+  try
+    Result.AddPair('name', Value.GetName);
+    Result.AddPair('description', Value.GetDescription);
+    Result.AddPair('parameters', TJSONObject.ParseJSONValue(Value.GetParameters));
+  except
+    on E: Exception do
+    begin
+      Result.Free;
+      raise;
+    end;
+  end;
 end;
 
 end.
diff --git a/OpenAI.Chat.pas b/OpenAI.Chat.pas
index 22fa42e..bb9f0ac 100644
--- a/OpenAI.Chat.pas
+++ b/OpenAI.Chat.pas
@@ -363,8 +363,8 @@ destructor TChat.Destroy;
 constructor TChatParams.Create;
 begin
   inherited;
-  // Model('gpt-3.5-turbo');
-  Model('gpt-3.5-turbo-0613');
+  Model('gpt-3.5-turbo');
+  // Model('gpt-3.5-turbo-0613');
   // Model('gpt-3.5-turbo-16k');
 end;
 
diff --git a/OpenAI.Embeddings.pas b/OpenAI.Embeddings.pas
index 6c7e627..5663971 100644
--- a/OpenAI.Embeddings.pas
+++ b/OpenAI.Embeddings.pas
@@ -90,8 +90,7 @@ destructor TEmbeddings.Destroy;
   if Assigned(FUsage) then
     FUsage.Free;
   for Item in FData do
-    if Assigned(Item) then
-      Item.Free;
+    Item.Free;
   inherited;
 end;
 
diff --git a/OpenAI.Utils.ChatHistory.pas b/OpenAI.Utils.ChatHistory.pas
index e11d92d..42a26c1 100644
--- a/OpenAI.Utils.ChatHistory.pas
+++ b/OpenAI.Utils.ChatHistory.pas
@@ -56,8 +56,10 @@ constructor TChatHistory.Create;
 end;
 
 procedure TChatHistory.DeleteByTag(const Tag: string);
+var
+  i: Integer;
 begin
-  for var i := 0 to Count - 1 do
+  for i := 0 to Count - 1 do
     if Items[i].Tag = Tag then
     begin
       Delete(i);
@@ -66,11 +68,14 @@ procedure TChatHistory.DeleteByTag(const Tag: string);
 end;
 
 procedure TChatHistory.SetContentByTag(const Tag, Text: string);
+var
+  i: Integer;
+  Item: TChatMessageBuild;
 begin
-  for var i := 0 to Count - 1 do
+  for i := 0 to Count - 1 do
     if Items[i].Tag = Tag then
     begin
-      var Item := Items[i];
+      Item := Items[i];
       Item.Content := Text;
       Items[i] := Item;
       Exit;
@@ -105,6 +110,9 @@ procedure TChatHistory.NewFunc(const FuncName, FuncResult, Tag: string);
 end;
 
 procedure TChatHistory.Notify(const Item: TChatMessageBuild; Action: TCollectionNotification);
+var
+  LastItem: TChatMessageBuild;
+  NeedLen: Int64;
 begin
   inherited;
   if FAutoTrim and (Action = TCollectionNotification.cnAdded) then
@@ -112,8 +120,8 @@ procedure TChatHistory.Notify(const Item: TChatMessageBuild; Action: TCollection
     while TextLength + FMaxTokensForQuery > FMaxTokensOfModel do
       if Count = 1 then
       begin
-        var LastItem := Items[0];
-        var NeedLen := LastItem.Content.Length - FMaxTokensForQuery;
+        LastItem := Items[0];
+        NeedLen := LastItem.Content.Length - FMaxTokensForQuery;
         LastItem.Content := LastItem.Content.Substring(LastItem.Content.Length - NeedLen, NeedLen);
         Items[0] := LastItem;
       end