Update app.py

Added calculate_walking_time_paris method

app.py

@@ -9,7 +9,12 @@ from Gradio_UI import GradioUI
 
 # Below is an example of a tool that does nothing. Amaze us with your creativity !
 @tool
-def calculate_walking_time_paris(start, end):
+def calculate_walking_time_paris(start, end) -> int:
+        """A tool that gets the actual walking time in minutes between two places.
+    Args:
+        start: A string representing starting point.
+        end: A string representing destinatin
+    """
     # This is a placeholder function. In a real scenario, this function would call a tool to get the actual walking time.
     # For now, we'll use predefined walking times for simplicity.
     walking_times = {