diff --git a/calculator.py b/calculator.py
index 5daac9a..746cae1 100644
--- a/calculator.py
+++ b/calculator.py
@@ -1,11 +1,43 @@
+from set import SetOperations
+
+
 class Calculator:
+    def __init__(self):
+        self.set_ops = SetOperations()
+
     def add(self, a, b):
         return a + b
+
     def subtract(self, a, b):
         return a - b
+
     def multiply(self, a, b):
         return a * b
+
     def divide(self, a, b):
         if b == 0:
             raise ValueError("Division by zero")
         return a / b
+
+    def set_union(self, left, right):
+        return self.set_ops.union(left, right)
+
+    def set_intersection(self, left, right):
+        return self.set_ops.intersection(left, right)
+
+    def set_difference(self, left, right):
+        return self.set_ops.difference(left, right)
+
+    def set_symmetric_difference(self, left, right):
+        return self.set_ops.symmetric_difference(left, right)
+
+    def set_is_subset(self, left, right):
+        return self.set_ops.is_subset(left, right)
+
+    def set_is_superset(self, left, right):
+        return self.set_ops.is_superset(left, right)
+
+    def evaluate(self, expression, mode="set"):
+        if mode != "set":
+            raise ValueError("Only set mode is supported in this repository state")
+        return self.set_ops.evaluate_expression(expression)
diff --git a/set.py b/set.py
new file mode 100644
index 0000000..dc788d5
--- /dev/null
+++ b/set.py
@@ -0,0 +1,69 @@
+import ast
+
+
+class SetOperations:
+    def parse_set(self, value):
+        if isinstance(value, set):
+            return value
+
+        if not isinstance(value, str):
+            raise ValueError("Set input must be a string or set")
+
+        text = value.strip()
+        if text == "{}":
+            return set()
+
+        try:
+            parsed = ast.literal_eval(text)
+        except (SyntaxError, ValueError) as exc:
+            raise ValueError("Invalid set input") from exc
+
+        if isinstance(parsed, (set, list, tuple)):
+            return set(parsed)
+
+        raise ValueError("Set input must be a set, list, or tuple")
+
+    def union(self, left, right):
+        return self.parse_set(left) | self.parse_set(right)
+
+    def intersection(self, left, right):
+        return self.parse_set(left) & self.parse_set(right)
+
+    def difference(self, left, right):
+        return self.parse_set(left) - self.parse_set(right)
+
+    def symmetric_difference(self, left, right):
+        return self.parse_set(left) ^ self.parse_set(right)
+
+    def is_subset(self, left, right):
+        return self.parse_set(left).issubset(self.parse_set(right))
+
+    def is_superset(self, left, right):
+        return self.parse_set(left).issuperset(self.parse_set(right))
+
+    def evaluate_expression(self, expression):
+        if not isinstance(expression, str) or not expression.strip():
+            raise ValueError("Expression must be a non-empty string")
+
+        text = expression.strip()
+        lowered = text.lower()
+
+        operations = [
+            (" union ", self.union),
+            (" intersection ", self.intersection),
+            (" difference ", self.difference),
+            (" symdiff ", self.symmetric_difference),
+            (" subset ", self.is_subset),
+            (" superset ", self.is_superset),
+        ]
+
+        for marker, function in operations:
+            if marker in lowered:
+                idx = lowered.index(marker)
+                left = text[:idx].strip()
+                right = text[idx + len(marker):].strip()
+                if not left or not right:
+                    raise ValueError("Invalid set expression")
+                return function(left, right)
+
+        raise ValueError("Invalid set expression")
diff --git a/test_calculator.py b/test_calculator.py
index 7cb79e9..c6f39ee 100644
--- a/test_calculator.py
+++ b/test_calculator.py
@@ -1,6 +1,7 @@
 import unittest
 from calculator import Calculator
 
+
 class TestCalculator(unittest.TestCase):
     # base test cases
     def setUp(self):
@@ -18,16 +19,49 @@ def test_multiply(self):
     def test_divide(self):
         self.assertEqual(self.calc.divide(2, 4), 0.5)
 
-    def test_divide(self):
+    def test_divide_negative(self):
         self.assertEqual(self.calc.divide(4, -2), -2)
-    
-    def test_divide_fail(self): # this will fail
+
+    def test_divide_fail(self):
         self.assertNotEqual(self.calc.divide(4, -2), 2)
 
     def test_divide_by_zero(self):
         with self.assertRaises(ValueError):
             self.calc.divide(5, 0)
 
-# Optional: this allows running the script directly
-    if __name__ == '__main__':
-        unittest.main() #
+    # set operation test cases
+    def test_set_union(self):
+        self.assertEqual(self.calc.set_union("{1,2}", "{2,3}"), {1, 2, 3})
+
+    def test_set_intersection(self):
+        self.assertEqual(self.calc.set_intersection("{1,2,3}", "{2,4}"), {2})
+
+    def test_set_difference(self):
+        self.assertEqual(self.calc.set_difference("{1,2,3}", "{2}"), {1, 3})
+
+    def test_set_symmetric_difference(self):
+        self.assertEqual(self.calc.set_symmetric_difference("{1,2,3}", "{2,4}"), {1, 3, 4})
+
+    def test_set_subset(self):
+        self.assertTrue(self.calc.set_is_subset("{1,2}", "{1,2,3}"))
+
+    def test_set_superset(self):
+        self.assertTrue(self.calc.set_is_superset("{1,2,3}", "{1,2}"))
+
+    def test_set_empty_set_boundary(self):
+        self.assertEqual(self.calc.set_union("{}", "{1,2}"), {1, 2})
+
+    def test_set_invalid_input(self):
+        with self.assertRaises(ValueError):
+            self.calc.set_union("{1,2}", "not_a_set")
+
+    def test_set_expression_union(self):
+        self.assertEqual(self.calc.evaluate("{1,2} union {2,3}"), {1, 2, 3})
+
+    def test_set_expression_invalid_operator(self):
+        with self.assertRaises(ValueError):
+            self.calc.evaluate("{1,2} merge {2,3}")
+
+
+if __name__ == '__main__':
+    unittest.main()