Calculator improvement example

calculator.py

# This is a calculator improvement used in the Medium post example.
# Original code without improvements available here: https://github.com/sobolevn/python-code-disasters/blob/master/python/my_first_calculator.py

def calculate(number1: int, number2: int, op_sign: str) -> float:
    mapper = {
        "+": number1 + number2,
        "-": number1 - number2,
        "/": number1 / number2,
        "*": number1 * number2
    }
    return mapper[op_sign]


print('Welcome to this calculator!')
print('It can add, subtract, multiply and divide whole numbers.')
try:
    num1 = int(input('Please choose your first number: '))
    sign = input('What do you want to do? +, -, /, or *: ')
    num2 = int(input('Please choose your second number: '))
    result = calculate(num1, num2, sign)
    print(f"""{num1} {sign} {num2} = {result}""")
except ZeroDivisionError:
    print("You can't divide by zero")
except KeyError:
    print("Invalid sign")
except ValueError:
    print("Invalid input")