Marks = [10, 23, 41, 75]
i= -1
while i >= -4:
print (Marks[i])
i = i+-1
Output:
75
41
23
10

(i) Mylist contains another list as an element. This type of list is known as "Nested List': Nested list is a list containing another list as an element.
(ii) Example: Mylist = [ "Welcome", 3.14, 10, [2,4,6] ]

Python programming language has four collections of data types such as List, Tuples, Set and Dictionary.

(i) In Python, a set is another type of collection data type. A'Set is a mutable and an unordered collection of elements without duplicates.
(ii) That means the elements within a set cannot be repeated. This feature used to include membership testing and eliminating duplicate elements. 

4

A list in Python is known as a "Sequence data type" like strings. It is an ordered collection of values enclosed within square brackets [ ]. Each value of a list is called as element.

(i) List is an ordered set of elements. But, a dictionary is a data structure that is used for matching one element (Key) with another (Value).
(ii) The index values can be used to access a particular element. But, in dictionary key represents index. Remember that, key may be a nunmber of a string.
(iii)  Lists are used to look up a value whereas a dictionary is used to take one value and look up another value.

Set Operations :
(i) Union : It includes all elements from two or more sets.
(ii) Intersection : It includes the common elements in two sets.
(iii) Difference : It includes all elements that are in first set (say set A) but not in the second set (say set B).
(iv) Symmetric difference : It includes all the elements that are in two sets (say sets A and B) but not the one that are common to two sets.

Output: [1,2,4,8,16]

Sort ( ) :
It sorts the element in list.
Syntax :
   List.sort(reverse=True|False,key=myfunc)
Sorts the element in list :
Both arguments are optional
(i) If reverse is set as True, list sorting is in descending order.
(ii) Ascending is default.
(iii) Key=myFunc; "myFunc" - the name of the user defined function that specifies the sorting criteria.
Example :
MyList = [Thilothamma', "Tharani', 'Anitha','SaiSree', 'Lavanya')
MyList.sort( )
print(MyList)
MyList.sort(reverse=True)
print(MyList)
Output :
['Anitha', 'Lavanya', 'SaiSree', 'Tharani', 'Thilothamma']
['Thilothamma', 'Tharani', 'SaiSree', 'Lavanya', 'Anitha']
 

(i) The elements of a list are changeable (mutable) whereas the elements of a tuple are unchangeable (immutable), this is the key difference between tuples and list.
(ii) The elements of a list are enclosed within square brackets[ ]. But the elements of a tuple are enclosed by parenthesis().
(iii) Iterating tuples is faster than list.

In Python, a tuple can be defined inside another tuple; called Nested tuple. In a nested tuple, each tuple is considered as an element. The for loop will be useful to access all the elements in a nested tuple.
Example:
Toppers = (("Vinodini", "XII-F", 98.7), ("Soundarya", "XII-H", 97.5),
("Tharani", "XII-F", 95.3), ("Saisri", "XII-G", 93.8))
for i in Toppers:
print(i)
Output:
('Vinodini', 'XII-F', 98.7)
('Soundarya', 'XII-H', 97.5)
('Tharani', 'XII-F', 95.3)
('Saisri', 'XII-G', 93.8)

Inserting elements in a list using insert ( ) :
(i) append ( ) function in Python is used to add more elements in a list. But, it includes elements at the end of a list.
(ii) If you want to include an element at your desired position, you can use insert ( ) function. The insert ( ) function is used to insert an element at any position of a list.
Syntax :
List.insert (position index, element)
Example :
>>> MyList=[34,98,47, Kannan,Gowrisankar','Lenin', 'Sreenivasan' ]
>>> print(MyList)
[34, 98, 47, 'Kannan', 'Gowrisankar', 'Lenin', 'Sreenivasan']
>>> MyList.insert(3, 'Ramakrishnan')
>>> print(MyList)
[34, 98, 47, 'Ramakrishnan', 'Kannan', 'Gowrisankar, 'Lenin', 'Sreenivasan']
Output : [34, 98, 47, 'Ramakrishnan', 'Kannan', 'Gowrisankar', 'Lenin', 'Sreenivasan']
(i) In the above cxample, insert( ) function inserts a new element 'Ramakrishnan' at the index value 3, ie. at the 4th position.
(ii) While inserting a new element in between the existing elements, at a particular location, the existing elements shifts one position to the right.