Update app.py

app.py

@@ -17,7 +17,7 @@ def reverse_parameters(arg1:str, arg2:int)-> str: #it's import to specify the re
         arg2: the second argument
     """
     return_value = arg1+' '+arg2
-    return return_value[][-1]
+    return return_value[::-1]
 
 @tool
 def get_current_time_in_timezone(timezone: str) -> str: