如何一次性更改类的所有实例的实例变量，Python

class MyClass:
    instances = []

    def __init__(self, var):
        self.var = var
        MyClass.instances.append(self)

    @classmethod
    def change_var(cls, new_var):
        for instance in cls.instances:
            instance.var = new_var

# 创建实例
obj1 = MyClass("var1")
obj2 = MyClass("var2")

# 修改所有实例的实例变量
MyClass.change_var("new_var")

# 打印所有实例的实例变量
for instance in MyClass.instances:
    print(instance.var)

class MyClass:
    instances = []

    def __init__(self, var):
        self.var = var
        MyClass.instances.append(self)

# 创建实例
obj1 = MyClass("var1")
obj2 = MyClass("var2")

# 修改所有实例的实例变量
for instance in MyClass.instances:
    instance.var = "new_var"

# 打印所有实例的实例变量
for instance in MyClass.instances:
    print(instance.var)