Linked_List with Python

#this is the part-B of c_b_i ,this module will insert a new node at the begining of head node
#this is node class
class Node:
    def __init__(self,data):
        self.data=data
        self.next=None
#this is linkedlist class which takes all the data from node class
class link_list:
    def __init__(self):
        self.head=None



    #this function is the main function which creates node by the user input

    def print(self):
        if self.head is None:
            #it is first node
            n_1=input("enter input for head node::")

            self.head = Node(n_1)
            #it is second node
            n_2=input("enter input for node_2::")
            second=Node(n_2)
            #it is third node
            n_3 = input("enter input for node_3::")
            third=Node(n_3)
            #now creat ing link from fist node to second node
            self.head.next=second
            #now creating link from second node to third
            second.next=third









    #to insert a element in the begining of a node
    def insert_at_begining(self):
        # assigning temperory head value in temp and using loop for traversing all the node and its data
        t_i = input("enter value for a node that will insert before the head node::")
        new_node = Node(t_i)
        new_node.next = self.head
        self.head = new_node
        temp = self.head
        print(temp)






    #to delete a node
    def deleting_node(self):

        key=input("enter value for key to be deleted:::")
        temp = self.head
        # If head node itself holds the key to be deleted
        if (temp is not None):
            if (temp.data == key):
                self.head = temp.next
                temp = None
                return

        # Search for the key to be deleted, keep track of the
        # previous node as we need to change 'prev.next'
        while (temp is not None):
            if temp.data == key:
                break
            prev = temp
            temp = temp.next

        # if key was not present in linked list
        if (temp == None):
            return

        # Unlink the node from linked list
        prev.next = temp.next

        temp = None







    #this function move the last element into the initial position
    def moveToFront(self):
        tmp = self.head
        sec_last = None  # To maintain the track of
        # the second last node

        # To check whether we have not received
        # the empty list or list with a single node
        if not tmp or not tmp.next:
            return

        # Iterate till the end to get
        # the last and second last node
        while tmp and tmp.next:
            sec_last = tmp
            tmp = tmp.next

        # point the next of the second
        # last node to None
        sec_last.next = None

        # Make the last node as the first Node
        tmp.next = self.head
        self.head = tmp





    #adding element in the end of linklist
    def add_last(self):
        v_1=input("enter a value for a node that will be in the End:::")

        temp = self.head
        # 1. Create a new node
        # 2. Put in the data
        # 3. Set next as None
        new_node=Node(v_1)

        # 4. If the Linked List is empty, then make the
        #    new node as head
        if self.head is None:
            self.head = new_node
            return

        # 5. Else traverse till the last node
        last = self.head
        while (last.next):
            last = last.next

        # 6. Change the next of last node
        last.next = new_node




    #this function replace the selected element with the user input
    def rep(self):
        v_1 = input("select value:::")

        v_2=input("enter new value:::")

        temp = self.head
        while temp.next is not None:
            if temp.data==v_1:
               temp.data=v_2
            temp=temp.next







    #it display the final output
    def display(self):
        temp = self.head
        while (temp):
            print("--->",temp.data)
            temp = temp.next


if __name__=="__main__":
 obj=link_list()

 obj.print()
 obj.display()
 obj.insert_at_begining()

 obj.display()
 obj.deleting_node()
 obj.display()
 obj.moveToFront()
 print("moving last element to front of link_list")
 obj.display()
 obj.add_last()
 obj.display()
 obj.rep()
 obj.display()