Create the fundamental Node and LinkedList classes using test driven development $($TDD$).$

Part $1-$ class Node

Create two files:

linkedlist.py and test$\_$linkedlist.py$.$ Implement unittests and functionality for a

Node class as described below.

Node

item: Any

link: Node $|$ None

init $($self$,$ item: Any, link: Optional$[$Node$])->$ None

repr$\_($self$)$ str

Figure $1$: Class diagram for Node. Note the use of expected types after colons. Node I None denotes it

can be a Node object or the None object. Optional $[$Node$]$ means there is an optional Node parameter that

defaults to None.

init$($self$,$ item:Any, link:Optional $[$Node$])->$ None

Creates a new Node object. link is either another Node or the None object

self$)$ str

Returns a string representaiton of the object, e$.$g$.$ Node$($Jake$)$

$\_$ This is a dunder method: $()$

TDD Flow:

init

Red: test$\_$linkedlist.py$,$ TestNode class:

Create a node, and assert it has the correct attributes, e$.$g$.$

node$1=$Node$(dots)$

self $.$ assertEqual $($node$1.$item, $...)$

self $.$ assertEqual $($node$1.$link, $...)$

Green:

linkedlist.py$,$ Node class: implement $\_-$

repr

Red: test$\_$linkedlist.py$,$ TestNode class:

Create a node, and assert it has the correct repr $()$ return, e$.$g$.$

node$1.)$

self $.$assertEqual $($repr $($node$1),$ "Node$(...)")$

Green:

linkedlist.py$,$ Node class: implement

Readability Note

You should $($almost$)$ always call dunder methods using their "magic" syntax. E$.$g$.$: