12.py

class Node:
    def __init__(self, data , data1):
        self.data1 = data
        self.data = data  
        self.next = None  
        self.prev = None  
    
class List:
    def __init__(self):        
        self.head = Node(None,None)
        self.head.next = self.head
        self.head.prev = self.head
        self.n = 0
        
    def get(self,ind):
        if ind >=  self.size() : 
            raise Exception('Out of list')
        x = self.head.next
        for i in range(ind) :
            x=x.next
        return x
    
    def insert_after(self, x, data, data1):
        y = Node(data,data1)
        self.n += 1
        y.prev = x
        y.next = x.next
        x.next = y
        y.next.prev = y
        return y
        
    def delete(self, x):
        if self.size()==0:
            raise Exception('List is empty')
        self.n -= 1
        x.prev.next = x.next
        x.next.prev = x.prev
        return x
        
    def find(self, val):
        x = self.head.next
        for i in range(self.size()) :
            if x.data == val :
                return x
            x=x.next
        return None
    
    def size(self):
        return self.n
      
    def is_empty(self):
        return self.n==0