Understand the Property Decorator in Python

example2.py

class Student:
    def __init__(self):
        self._score = 0

    def set_score(self, s):
        if 0 <= s <= 100:
            self._score = s
        else:
            raise ValueError('The score must be between 0 ~ 100!')
Yang = Student()
Yang.set_score(100)
print(Yang._score)
# 100