diff --git a/solutions/basic_calculator/main.py b/solutions/basic_calculator/main.py
index 7f9aacaec..39d6bd597 100644
--- a/solutions/basic_calculator/main.py
+++ b/solutions/basic_calculator/main.py
@@ -1,5 +1,3 @@
-
-
 """
 A module for performing basic arithmetic operations: addition, subtraction,
 multiplication, and division.
@@ -11,11 +9,13 @@
 Author: Ana Isabel Murillo
 """
 
+
 def calculate(operation: str, num1: float, num2: float) -> float:
     """Performs the specified arithmetic operation on two numbers.
 
     Parameters:
-        operation: str, the operation to perform ('add', 'subtract', 'multiply', 'divide')
+        operation: str, the operation to perform
+        ('add', 'subtract', 'multiply', 'divide')
         num1: float, the first number
         num2: float, the second number
 
@@ -38,15 +38,18 @@ def calculate(operation: str, num1: float, num2: float) -> float:
             ...
         ValueError: Cannot divide by zero.
     """
-    if operation == 'add':
+    if operation == "add":
         return num1 + num2
-    elif operation == 'subtract':
+    elif operation == "subtract":
         return num1 - num2
-    elif operation == 'multiply':
+    elif operation == "multiply":
         return num1 * num2
-    elif operation == 'divide':
+    elif operation == "divide":
         if num2 == 0:
             raise ValueError("Cannot divide by zero.")
         return num1 / num2
     else:
-        raise ValueError(f"Invalid operation '{operation}'. Valid operations are: add, subtract, multiply, divide.")
+        raise ValueError(
+            f"Invalid operation '{operation}'. Valid operations are: "
+            "add, subtract, multiply, divide."
+        )
diff --git a/solutions/tests/test_basic_calculator.py b/solutions/tests/test_basic_calculator.py
index 58550519b..1e9d80b76 100644
--- a/solutions/tests/test_basic_calculator.py
+++ b/solutions/tests/test_basic_calculator.py
@@ -10,45 +10,46 @@
 Author: Ana Isabel Murillo
 """
 
-from solutions.basic_calculator.main import calculate
 import unittest
 
+from solutions.basic_calculator.main import calculate
+
 
 class TestCalculate(unittest.TestCase):
     """Test suite for the calculate function."""
 
     def test_addition(self):
         """It should correctly add two numbers."""
-        self.assertEqual(calculate('add', 5, 3), 8.0)
-        self.assertEqual(calculate('add', -5, -3), -8.0)
-        self.assertEqual(calculate('add', 0, 5), 5.0)
+        self.assertEqual(calculate("add", 5, 3), 8.0)
+        self.assertEqual(calculate("add", -5, -3), -8.0)
+        self.assertEqual(calculate("add", 0, 5), 5.0)
 
     def test_subtraction(self):
         """It should correctly subtract the second number from the first."""
-        self.assertEqual(calculate('subtract', 10, 4), 6.0)
-        self.assertEqual(calculate('subtract', -5, -5), 0.0)
-        self.assertEqual(calculate('subtract', 0, 5), -5.0)
+        self.assertEqual(calculate("subtract", 10, 4), 6.0)
+        self.assertEqual(calculate("subtract", -5, -5), 0.0)
+        self.assertEqual(calculate("subtract", 0, 5), -5.0)
 
     def test_multiplication(self):
         """It should correctly multiply two numbers."""
-        self.assertEqual(calculate('multiply', 7, 3), 21.0)
-        self.assertEqual(calculate('multiply', -2, 3), -6.0)
-        self.assertEqual(calculate('multiply', 0, 10), 0.0)
+        self.assertEqual(calculate("multiply", 7, 3), 21.0)
+        self.assertEqual(calculate("multiply", -2, 3), -6.0)
+        self.assertEqual(calculate("multiply", 0, 10), 0.0)
 
     def test_division(self):
         """It should correctly divide the first number by the second."""
-        self.assertEqual(calculate('divide', 9, 3), 3.0)
-        self.assertEqual(calculate('divide', -6, 3), -2.0)
-        self.assertAlmostEqual(calculate('divide', 7, 2), 3.5)
+        self.assertEqual(calculate("divide", 9, 3), 3.0)
+        self.assertEqual(calculate("divide", -6, 3), -2.0)
+        self.assertAlmostEqual(calculate("divide", 7, 2), 3.5)
 
     def test_division_by_zero(self):
         """It should raise a ValueError when attempting to divide by zero."""
         with self.assertRaises(ValueError) as context:
-            calculate('divide', 5, 0)
+            calculate("divide", 5, 0)
         self.assertEqual(str(context.exception), "Cannot divide by zero.")
 
     def test_invalid_operation(self):
         """It should raise a ValueError for an invalid operation."""
         with self.assertRaises(ValueError) as context:
-            calculate('invalid_op', 5, 3)
+            calculate("invalid_op", 5, 3)
         self.assertIn("Invalid operation", str(context.exception))