关于类的继承的问题，请教！

下面的一段代码，可以正常运行，我将Teacher类和Student类后面括号里的基类为空后，照样可以正常运行，请问，这是为什么？
#!/usr/bin/env python
#coding=utf8
class SchoolMember:
def __init__(self, name, age):
self.name = name
self.age = age
print(u*（初始化学校成员：{0}）*.format(self.name))
def tell(self):
print(u*姓名：“{0}” 年龄：“{1}”*.format(self.name, self.age), end = **)
class Teacher(SchoolMember):
def __init__(self, name, age, salary):
SchoolMember.__init__(self, name, age)
self.salary = salary
print(u*（初始化老师：{0}）*.format(self.name))
def tell(self):
SchoolMember.tell(self)
print(u*薪水：{0:d}*.format(self.salary))
class Student(SchoolMember):
def __init__(self, name, age, marks):
SchoolMember.__init__(self, name, age)
self.marks = marks
print(u*（初始化学生：{0}）*.format(self.name))
def tell(self):
SchoolMember.tell(self)
print(u*成绩：“{0:d}”*.format(self.marks))
t = Teacher(u*王老师*, 30, 5000)
s = Student(u*周同学*, 18, 100)
print(*** * 40)
members = (t, s)
for member in members:
member.tell()