Write a note on self argument used in python class function.

Explain the working of the following program. class Sample:
def _init_(self, num):
print("Constructor of class Sample ...")
self.num=num
print("The value is :", num)
S=Sample(10)

Why the following program give an error while displaying the value of n2. Give Reason.

Fill up the blanks in the following program to get the output:
Value of x = 10
Value of y = 20
Sum of x and y= 30
Class sample:
x, __ = 10, 20 -------------------1
s = -------------------------2
print ("value of x =", __ ) ------------3
print ("value of y =", __ ) -------------4
print ("sum of x and y =", __ ) --------5

Read the following program. Answer the following question. Class sample:
x, y= 10, 20
s= sample ()
print (s. x + s. y)
1. What does sample denotes?
2. What does x, y denotes?
3. What does s denotes?