Stuff
+ name:str+ age+ balance+ salary+position+dept+school_obj
+ panch_card()
Class
+ course_obj+ semester 学期+ school_obj+ stu_list = []
BranchSchool
+ name:str+ addr:str+ website+balance
+ count_stu_num()- pay_salary()- staff_enrollment(staff_obj)
Student
+ name:str+ age+ balance+class_obj
+ panch_card()- pay_tuition() 交会费
School
Tercher
+ panch_card()+teach_class(class_obj)
Course
+ name+ price+ outline 教学大纲
