经常看到很多函数里使用了 *args 和 **kwargs，示例如：
function(params, *args, **kwargs)而，该函数如何使用呢，参数如何通过 args 和 kwargs 进行传递的呢？
1. 函数一般形式
首先，定义如下打印名字的函数：
def characters(name1, name2, name3):
print(name1, name2, name3)运行函数：
#
characters("Iron Man", "Black Panther", "Captain America")
#输出：
#Iron Man Black Panther Captain America其中，name1、name2、name3 分别对应 Iron Man,Black Panther, Captain America.
再次运行函数：
characters("Iron Man", "Black Panther", "Captain America", "Hulk")
#出现报错：
#TypeError: characters() takes 3 positional arguments but 4 were given
此时，对于函数输入超过明确定义的变量的，则函数就会报错.
2. 使用 *args
*args 适用于函数传递的参数数量未知的场景.
其中，args 前的*确保了参数具有可变长度.
示例如，定义函数：
def friends(*args):
print(args)运行函数：
friends("Sachin", "Rishu", "Yashwant", "Abhishek")
#输出：
#('Sachin', 'Rishu', 'Yashwant', 'Abhishek')
其中，args是元组tuple形式.
再者，示例函数如：
def friends(greet, *args):
for friend in args:
print(f"{greet} to Python, {friend}")运行函数：
greet = "Welcome"
friends(greet, "Sachin", "Rishu", "Yashwant", "Abhishek")
#输出：
'''
Welcome to Python, Sachin
Welcome to Python, Rishu
Welcome to Python, Yashwant
Welcome to Python, Abhishek
'''实际上可以将 args 替换为任何其他名字，如：
def heroes(country, *characters):
for character in characters:
print(f"{character} is from {country}.")3. 使用 **kwargs
kwargs 是 keyword argument 的缩写.
*kwargs 类似于 args. 不同之处在与，kwargs 是包含 keyword 或 named 参数. 其是 dict 形式，以 key-value 参数传递.
示例函数如：
def hello(**kwargs):
print(type(kwargs))
for key, value in kwargs.items():
print(f"{key} is {value}.")运行函数：
hello(One = "Red", two = "Green", three = "Blue")
#输出：
'''
<class 'dict'>
One is Red.
two is Green.
three is Blue.
'''kwargs 也可以替换为其他字符，如：
def hello(write, **color):
print(write)
for key, value in color.items():
print(f"{key} is {value}.")4. 同时使用 args 和 *kwargs
如：
function(params, *args, **kwargs)注：args 只能在 kwargs 前面.
示例函数如：
def friends(greet, *args, **kwargs):
for names in args:
print(f"{greet} to the Programming zone {names}")
print("\nI am Veronica and I would like to announce your roles:")
for key, value in kwargs.items():
print(f"{key} is a {value}")运行函数：
greet = "Welcome"
names = ["Sachin", "Rishu", "Yashwant", "Abhishek"]
roles = {"Sachin":"Chief Instructor", "Rishu":"Engineer",
"Yashwant":"Lab Technician", "Abhishek":"Marketing Manager"}
friends(greet, *names, **roles)
#输出：
'''
Welcome to the Programming zone Sachin
Welcome to the Programming zone Rishu
Welcome to the Programming zone Yashwant
Welcome to the Programming zone Abhishek
I am Veronica and I would like to announce your roles:
Sachin is a Chief Instructor
Rishu is a Engineer
Yashwant is a Lab Technician
Abhishek is a Marketing Manager
'''5. Unpacking Operator
单个 * 用于 unpack iterable;
两个 * 用于 unpack dict.