python如何实例化对象

# coding: utf-8
# 创建一个类，类名称第一个字母大写,可以带括号也可以不带括号
 
class Student(): 
    student_count = 0 
    def __init__(self, name, salary):
        self.name = name
        self.age = salary
        Student.student_count += 1 
    def display_count(self):
        print('Total student {}'.format(Student.student_count)) 
    def display_student(self):
        print('Name: {}, age: {}'.format(self.name,self.age)) 
    def get_class(self):
        if self.age >= 7 and self.age < 8:
            return 1
        if self.age >= 8 and self.age < 9:
            return 2
        if self.age >= 9 and self.age < 10:
            return 3
        if self.age >= 10 and self.age < 11:
            return 4
        else:
            return  0