Method __mul__

Chapter 11 - PS/06_problem6.py:11–13

(self, other)

        return result

    def __mul__(self, other):
        result = self.x * other.x + self.y * other.y + self.z * other.z
        return result

    def __str__(self):
        return f"{self.x}i + {self.y}j + {self.z}k"