Complete in Python with comments, thank you.

Recall that stacks and queues are abstract data types $($ADTs$).$ They support certain basic

operations, but these operations can be implemented in different ways. In class, we used a linked

list to build a stack and a queue. In this problem, you'll do the same thing using Python's

built$-$in list instead of a linked list.

In a file named custom$\_$adts.py$,$ do the following:

$($a$)(5$ points$)$ Write a Stack class that implements a stack ADT using a Python list to store

the stack elements. Use index $0$ of the list as the "bottom" of the stack. Your class needs

the following components:

A constructor that initializes the list

A method that returns a string containing the elements in the stack

A size method that returns the number of elements in the stack

A push method that adds a new element to the top of stack

A pop method that removes and returns the element at the top of the stack. If the

stack is empty, this method returns None.

A peek method that returns $($without removing$)$ the element at the top of the stack.

If the stack is empty, this method returns None.

$($b$)(5$ points$)$ Write a Queue class that implements a queue ADT using a Python list to store

the queue elements. Use index $0$ of the list as the "back" of the queue. Your class needs

the following components:

A constructor that initializes the list

A $\_$str$\_$method that returns a string containing the elements in the queue

A size method that returns the number of elements in the queue

An enqueue method that adds a new element to the back of the queue

A dequeue method that removes and returns the element at the front of the queue. If

the queue is empty, this method returns None.

A peek method that returns $($without removing$)$ the element at the front of the queue.

If the queue is empty, this method returns None.