Add calculate_factorial fuction

app.py

@@ -9,14 +9,25 @@ from Gradio_UI import GradioUI
 
 # Below is an example of a tool that does nothing. Amaze us with your creativity !
 @tool
-def my_custom_tool(arg1:str, arg2:int)-> str: #it's import to specify the return type
-    #Keep this format for the description / args / args description but feel free to modify the tool
-    """A tool that does nothing yet 
+def calculate_factorial(n: int) -> int:
+    """
+    A tool that calculates the factorial of an integer.
+
     Args:
-        arg1: the first argument
-        arg2: the second argument
+    n (int): The number for which the factorial is to be calculated. Must be a non-negative integer.
+    
+    Returns:
+    int: The factorial value of n.
+
     """
-    return "What magic will you build ?"
+    if n < 0:
+        raise ValueError("The number must be a non-negative integer.")
+    
+    factorial = 1
+    for i in range(2, n + 1):
+        factorial *= i
+    
+    return factorial
 
 @tool
 def get_current_time_in_timezone(timezone: str) -> str: