python的继承

if __name__ == "__main__":
    print "Hello World"
class Person:
    Population=0;
    def __init__(self,name,age):
        self.name=name;
        self.age=age;
        print '(Initialized SchoolMember: %s)' % self.name
      #Person.Population=Person.Population+1;
    def tell(self):
            print self.name;
            print 'Name:"%s" Age:"%s"' % (self.name, self.age);

class Teacher(Person):
    def __init__(self, name, age, salary):
        Person.__init__(self,name,age);
        self.salary=salary;
        print '(Initialized Teacher: %s)' % self.name;
    def tell(self):
       Person.tell(self)
       print 'Salary: "%d"' % self.salary;

class Student(Person):
    def __init__(self, name, age, marks):
       Person.__init__(self, name, age)
       self.marks = marks
       print '(Initialized Student: %s)' % self.name
    def tell(self):
       Person.tell(self)
       print 'Marks: "%d"' % self.marks

t = Teacher('Mrs. Shrividya', 40, 30000)
s = Student('CY', 22, 75)

persons= [t, s]
for person in persons:
    person .tell()