diff --git a/examples/agent.py b/examples/agent.py
index ae5727fc8..158537a19 100644
--- a/examples/agent.py
+++ b/examples/agent.py
@@ -18,7 +18,7 @@
 salaries_df = pd.DataFrame(salaries_data)
 
 
-llm = OpenAI("sk-lyDyNVyBwnykr1lJ4Yc7T3BlbkFJtJNyJlKTAvUa2E2D5Wdb44")
+llm = OpenAI("OPEN_API_KEY")
 agent = Agent([employees_df, salaries_df], config={"llm": llm}, memory_size=10)
 
 # Chat with the agent
diff --git a/pandasai/agent/__init__.py b/pandasai/agent/__init__.py
index 6ae93b42d..ef2c798dc 100644
--- a/pandasai/agent/__init__.py
+++ b/pandasai/agent/__init__.py
@@ -19,13 +19,13 @@ class Agent:
 
     _memory: Memory
     _lake: SmartDatalake = None
-    logger: Logger = None
+    logger: Optional[Logger] = None
 
     def __init__(
         self,
         dfs: Union[DataFrameType, List[DataFrameType]],
         config: Optional[Union[Config, dict]] = None,
-        logger: Logger = None,
+        logger: Optional[Logger] = None,
         memory_size: int = 1,
     ):
         """