Python code for " Simple Calculator " . Computer science project

HERE'S A PYTHON CODE FOR SIMPLE CALCULATOR:

SOURCE CODE -

def add(x, y):
    return x + y


def subtract(x, y):
    return x - y


def multiply(x, y):
    return x * y


def divide(x, y):
    return x / y


print('Select operation.')
print('1. Add')
print('2. Subtract')
print('3. Multiply')
print('4. Divide')

while True:
    choice = input('Enter choice (1/2/3/4): ')

    if choice in ('1', '2', '3', '4'):
        num1 = float(input('Enter first number: '))
        num2 = float(input('Enter second number: '))

        if choice == '1':
            print(num1, '+', num2, '=', add(num1, num2))

        elif choice == '2':
            print(num1, '-', num2, '=', subtract(num1, num2))

        elif choice == '3':
            print(num1, '*', num2, '=', multiply(num1, num2))

        elif choice == '4':
            print(num1, '/', num2, '=', divide(num1, num2))
        break
    else:
        print('Invalid input.')