3 files changed, 12 insertions, 5 deletions

diff --git a/g4f/Provider/Aivvm.py b/g4f/Provider/Aivvm.py
index 97c9dff0..c38c4a74 100644
--- a/g4f/Provider/Aivvm.py
+++ b/g4f/Provider/Aivvm.py
@@ -2,7 +2,7 @@ from __future__ import annotations
 import requests
 
 from .base_provider import BaseProvider
-from ..typing import Any, CreateResult
+from ..typing import CreateResult
 
 models = {
     'gpt-3.5-turbo': {'id': 'gpt-3.5-turbo', 'name': 'GPT-3.5'},
@@ -26,8 +26,14 @@ class Aivvm(BaseProvider):
     def create_completion(cls,
         model: str,
         messages: list[dict[str, str]],
-        stream: bool, **kwargs: Any) -> CreateResult:
-        
+        stream: bool,
+        **kwargs
+    ) -> CreateResult:
+        if not model:
+            model = "gpt-3.5-turbo"
+        elif model not in models:
+            raise ValueError(f"Model are not supported: {model}")
+    
         headers = {
             "authority"          : "chat.aivvm.com",
             "accept"             : "*/*",
diff --git a/g4f/__init__.py b/g4f/__init__.py
index c0f70d8a..d6388fb5 100644
--- a/g4f/__init__.py
+++ b/g4f/__init__.py
@@ -64,7 +64,8 @@ class ChatCompletion:
         
         model, provider = get_model_and_provider(model, provider, False)
 
-        if not issubclass(provider, AsyncProvider) and not issubclass(type(provider), AsyncProvider):
+        provider_type = provider if isinstance(provider, type) else type(provider)
+        if not issubclass(provider_type, AsyncProvider):
             raise Exception(f"Provider: {provider.__name__} doesn't support create_async")
 
         return await provider.create_async(model.name, messages, **kwargs)
diff --git a/g4f/models.py b/g4f/models.py
index 71fd6b18..01b42106 100644
--- a/g4f/models.py
+++ b/g4f/models.py
@@ -24,7 +24,7 @@ from .Provider   import (
 class Model:
     name: str
     base_provider: str
-    best_provider: Union[type[BaseProvider], tuple[type[BaseProvider]]] = None
+    best_provider: Union[type[BaseProvider], RetryProvider] = None
 
 # Config for HuggingChat, OpenAssistant
 # Works for Liaobots, H2o, OpenaiChat, Yqcloud, You