input: Write a python function to create a Calculator class with methods for addition, subtraction, multiplication, and division.
  assert Calculator().add(1, 2) == 3
  assert Calculator().subtract(5, 3) == 2
  assert Calculator().multiply(4, 6) == 24
  assert Calculator().divide(10, 2) == 5
output: class Calculator:
      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("Cannot divide by zero")
          return a / b