An introduction to python's function knowledge

formal parameter
	Arguments written in parentheses in the function definition phase
actual parameter
	Arguments passed in parentheses during function call phase

Relationship between formal and real parameters
	You can think of a formal parameter as a variable name，Real parameters are viewed as variable values
    Temporary binding during function call phase，Disconnect at the end of the function run
Manifestations of Formal Reference		variable name
Real parameters are represented in a variety of ways	（Get to the heart of it  data value）

position parameter
	Parameters to be filled in from left to right
positional parameters
	Variable names filled in from left to right in the function definition phase
positional real parameter
	Data values filled in from left to right in the function call phase

keyword real parameter（It's possible to break the order of positions）
	The function call phase passes the name of the formal parameter=Form of data values  transmit a value
1.Position shapes and position real parameters in the function call phase，Binding by location
2.When binding position parameters, one more will not work and one less will not work.
recount (e.g. results of election)： The simpler the format, the higher the ranking，The more complex, the further back.	

1.Functions work fine no matter how many positional parameters are passed in
 variable length parameter
 def func(x,y,*a):
     print(x,y,a)
 func()  # ()
 func(1)  # (1,)
 func(1, 2, 3, 4, 5, 6, 7)  # (1, 2, 3, 4, 5, 6, 7)
 func(1,2)  # 1 2 ()
 func(1,2,3,4,5,6,7,8,9)  # 1 2 (3, 4, 5, 6, 7, 8, 9)
 func(1,2)  # 1 2 (3, 4, 5, 6, 7, 8, 9)
*Used in formal parameters to receive redundant positional parameters and organized into tuples of rows assigned to the*trailing variable name    

2.Functions work no matter how many keywords are passed into them
 def index(x, y, **b):
     print(x, y, b)
 index()  # {}
 index(a=1,b=2,c=3,d=4)  # {'a': 1, 'b': 2, 'c': 3, 'd': 4}
 index(y=2, x=1)  # 1 2 {}
 index(y=2, x=1, u=222, k=111, l=444)  # 1 2 {'u': 222, 'k': 111, 'l': 444}
**Used in formal parameters to receive redundant keyword arguments and organized as a dictionary assigned to the**trailing variable name  
*utilization
	will list、Breaking up data within a tuple
**utilization    
	will break up the key-value pairs of the dictionary into keyword arguments passed into the

	1.built-in namespace
            print()
        	len()
	2.global namespace       
    	pyCode written at the top of the document
    	    name = 'jason'  # name global
            def func():  # func global
                pass
            if 1:
                a = 123  # a global
            for i in range(10):
                print(i)  # i global
            while True:
                a = 123  # a global
	3.Local namespace
    	函数体代码运行之后产生的都是Local namespace