字典总结
字典概念
字典是“键名-数值对”的无序集合，键是唯一的、不可变的，值是可变的。
字典初始化
my_dict = {"Wang":1998,"Liu":1998,"Guo":1997}
my_dict["Wang"]
1998
my_dict = {"Wang":1998,"Liu":1998,"Guo":1997}
my_dict['Wang'] = 1996
my_dict
{'Wang': 1996, 'Liu': 1998, 'Guo': 1997}
my_dict = {"Wang":1998,"Liu":1998,"Guo":1997}
my_dict["Tan"]
