Variabel instance vs variabel class

class Student:
    # Variabel class: digunakan bersama oleh semua instance
    school = "Python High School"
    
    def __init__(self, name, grade):
        # Variabel instance: unik untuk setiap siswa
        self.name = name
        self.grade = grade

alice = Student("Alice", "A")
bob = Student("Bob", "B")

print(alice.name)  # Alice
print(bob.name)    # Bob
print(alice.grade) # A
print(bob.grade)   # B

print(alice.school)     # Python High School
print(bob.school)       # Python High School
print(Student.school)   # Python High School

Student.school = "Python Academy"

print(alice.school)   # Python Academy
print(bob.school)     # Python Academy

Alice
Bob
A
B
Python High School
Python High School
Python High School
Python Academy
Python Academy

alice.age = 16  # Ini membuat variabel instans
print(alice.age)  # 16
# print(bob.age)  # Ini akan menyebabkan error karena bob tidak memiliki age