added clear api function

src/main.py

@@ -36,6 +36,10 @@ class ChatWrapper:
                 raise ValueError(f'Invalid chain_type: {chain_type}')
         else:
             self.chain = None
+    
+    def clear_api_key(self):
+        if hasattr(self, 'api_key'):
+            del self.api_key
 
     def __call__(self, inp: str):
         self.lock.acquire()
@@ -49,7 +53,7 @@ class ChatWrapper:
         except Exception as e:
             self.history.append((inp, f"An error occurred: {e}"))
         finally:
-            self.api_key = ''  # API key is cleared after running each chain
+            self.clear_api_key() # API key is cleared after running each chain in the class
             self.lock.release()
 
         return self.history