In Python, one way to implement a linked list is as a sequence class, as discussed in the chapter on operator overloading. Implement a single-linked list as a sequence class. Implement addhead() and addtail() methods to add an item to the start and the end of the linked list, respectively. Implement a pop() method to remove the first item of the linked list and return its value. For the __getitem__() and __setitem__() methods, the key is the index of the item in the linked list. Also implement the __contains__() and __len__() methods. Implement a __repr__() method to display the contents of the linked list. Note that, by using this implementation, you can now use a for ... in ... construction to traverse the linked list (as well as using indices).

Build ontop of the code previously given:

class SingleNode:
    def __init__( self, value, nextnode ):
        self.value = value
        self.nextnode = nextnode
        
class SingleLinkedList:
    def __init__( self ):
        self.head = None
        self.tail = None
    def add( self, value ):
        node = SingleNode( value, self.head )
        self.head = node
        if self.tail == None:
            self.tail = self.head
    def remove( self ):
        if self.head == self.tail:
            self.head = None
            self.tail = None
        else:
            self.head = self.head.nextnode
    def append( self, value ):
        node = SingleNode( value, None )
        if self.tail == None:
            self.head = node
            self.tail = node
        else:
            self.tail.nextnode = node
            self.tail = node

Note: The submission of this exercise is in markdown and therefore won’t be tested. Use your preferred code editor or Papyrus¹ to test your code.