Create calculator.py

tools/calculator.py

@@ -0,0 +1,25 @@
+# tools/calculator.py
+import ast, operator as op
+
+# Allowed operators
+_ops = {
+    ast.Add: op.add, ast.Sub: op.sub, ast.Mult: op.mul,
+    ast.Div: op.truediv, ast.Pow: op.pow, ast.Mod: op.mod,
+    ast.USub: op.neg
+}
+
+def _safe_eval(node):
+    if isinstance(node, ast.Expression): 
+        return _safe_eval(node.body)
+    if isinstance(node, ast.Constant): 
+        return node.value
+    if isinstance(node, ast.BinOp): 
+        return _ops[type(node.op)](_safe_eval(node.left), _safe_eval(node.right))
+    if isinstance(node, ast.UnaryOp): 
+        return _ops[type(node.op)](_safe_eval(node.operand))
+    raise ValueError("Unsupported expression")
+
+def calculator(expression: str) -> str:
+    """Safely evaluate arithmetic expressions and return result as string."""
+    tree = ast.parse(expression, mode="eval")
+    return str(_safe_eval(tree))