Using Global and Local variable in same code:
x=8  # x is a global variable
def loc():
global x
y = "local"
x=x * 2
print(x)
print(y)
loc()
Output:
16
local

The return statement:
(i) The return statement causes your function to exit and returns a value to its caller. The it point of functions in general is to take inputs and return something.
(ii) The return statement is used when a function is ready to return a value to its caller. So, only one return statement is executed at run time even though the function contains multiple return statements.
(iii) Any number of 'return' statements are allowed in a function definition but only one of them is executed at run time.

(i) In Python the default argument is an argument that takes a default value if no value is provided in the function call.
(ii) The following example uses default arguments, that prints default salary when no argument is passed.
(iii) Example:
def printinfo( name, salary = 3500):
print ("Name: ", name)
print ("Salary: ", salary)
return
printinfo("Mani")
When the above code is executed, it produces the following output
Output:
Name: Mani
Salary: 3500
When the above code is changed as print info("Ram", 2000) it produces the following output:
Output:
Name: Ram
Salary: 2000

(i) "Required Arguments" are the arguments passed to a function in correct positional order. Here, the number of arguments in the function call should match exactly with the function definition.
(ii) Atleast one parameter to prevent syntax errors to get the required output.
(iii) Example:
def printstring(str):
print ("Example - Required arguments")
print (str)
return
# Now you can call printstring() function
printstring ("Welcome")
Output:
Example - Required arguments
Welcome