SOLID - Single responsability

s1.py

def main(a, b, operation):
    result = None

    if operation == "sum":
        result = a + b
    elif operation == "sub":
        result = a - b
    elif operation == "mult":
        result = a * b
    elif operation == "div":
        result = a / b
    
    a = ""
    print(result)
    pass
  
main(5, 6, "sum")

s2.py

class Calculator:

    def __init__(self, a, b):
        self._a = a
        self._b = b
        pass

    def calculate(self, operation):

        if operation == "sum":
            return self._a + self._b
        elif operation == "sub":
            return self._a - self._b
        elif operation == "mult":
            return self._a * self._b
        elif operation == "div":
            return self._a / self._b
        else:
            raise ValueError("Operation not found")


def main(a, b, operation):
    
    c = Calculator(a, b)
    print(c.calculate(operation))
    pass


main(5, 6, "sum")