class Node:
    def __init__(self, data):
        self.head = None
        self.data = data
        self.tail = None


class DoublyLinkedList:
    def __init__(self):
        self.head = None

    def insertNode(self, data):
        new_node = Node(data)
        if self.head == None:
            self.head = new_node
        else:
            last = self.head
            tail = ''
            while tail is not None:
                if last.tail == None:
                    tail = None
                else:
                    last = last.tail

            new_node.head = last
            last.tail = new_node

    def traverse_data(self):
        if self.head == None:
            print('No nodes available to traverse')

        else:
            last = self.head
            tail = ''
            while tail is not None:
                if last.tail == None:
                    print(last.data)
                    tail = None
                else:
                    print(last.data)
                    last = last.tail

    def delete_data(self, data):
        if self.head == None:
            print('ERROR: No data is present for deletion')
        else:
            last = self.head
            data_present = True

            while last.data is not data:
                if  last.tail is None:
                    print('Your data is not yet present')
                    data_present = False
                    break
                last = last.tail
            if data_present:
                if last.tail is not None:
                    last.head.tail = last.tail
                else:
                    last.head.tail = None

                del last
            return


dbll = DoublyLinkedList()

dbll.insertNode('a')
dbll.insertNode('b')
dbll.insertNode('c')
dbll.insertNode('d')

dbll.insertNode('e')
dbll.insertNode('f')
dbll.insertNode('g')

dbll.delete_data('g')

dbll.insertNode('h')
dbll.insertNode('i')
dbll.insertNode('j')
dbll.insertNode('k')
dbll.insertNode('l')

dbll.traverse_data()


'''
OUTPUT:-
=======
a
b
c
d
e
f
h
i
j
k
l
'''