python类创建和调用方法

#Filename:doginsta.py
#类创建和调用方法
class Dog(object):
    "define Dog class"
    def setName(self,name):
        self.name = name
    def greet(self):
        print("Hi,I am called %s." % self.name)
if __name__ == '__main__':  #这一行写错，没有输出结果 should be:'__main__'
    dog = Dog()
    dog.setName("Sara")
    print(dog.greet())

#--------------------------------------------------------
print("haha ,cuole!,wrong!pay attention to it '__main__'!")
#--------------------------------------------------------------
class Roster:
    "students and teacher class"
    teacher = "maya"
    students = ['list',"kv" ]
    def __init__(self,tn='mayun'):
        self.teacher=tn
    def add(self, sn):
        self.students.append(sn)
    def remove(self, sn):
        self.students.remove(sn)
    def print_all(self):
        print("Teacher:", self.teacher)
        print("Students:", self.students)
if __name__ == '__main__':
    roster = Roster()
    roster.add("tutu")
    roster.print_all()
    roster.remove("kv")
    roster.print_all()