added calculator tool in app.py

app.py

@@ -1,3 +1,5 @@
+from math import *
+
 from smolagents import CodeAgent,DuckDuckGoSearchTool, HfApiModel,load_tool,tool
 import datetime
 import requests
@@ -18,6 +20,31 @@ def my_custom_tool(arg1:str, arg2:int)-> str: #it's import to specify the return
     """
     return "What magic will you build ?"
 
+@tool
+def calculator(math_expr: str) -> tuple[float | None, str]:
+    """Calculates any math expression, that is passed as a string 
+    Args:
+        math_expr (str): math expression to be evaluated.
+            Expression can contain any operations and constants from math standart python library and basic math operations, 
+            like: +,-,/,*,** and so on.
+    Returns:
+        - float result of math expression evaluation (is expression was evaluated correctly, else: None)
+        - status_code: 'ok' or 'failed'
+    Examples:
+        1) 
+        >>> calculator(math_expr='3 + 5')[0]
+        >>> 8
+
+        2) 
+        >>> calculator(math_expr='(exp(-3.5)**2 - sin(pi/2)) / log2(3)')[0]
+        >>> -0.630354420107644
+    """
+    try:
+        return float(eval(math_expr)), 'ok' # status_code
+    except Exception as e:
+        print(f"Exception raised when trying to compute expression {math_expr}")
+        return None, 'failed'
+
 @tool
 def get_current_time_in_timezone(timezone: str) -> str:
     """A tool that fetches the current local time in a specified timezone.