1

class Node():
    def __init__(self,data):
        self.prev = None
        self.next = None
        self.data = data

class DLL():
    def __init__(self):
        self.head =None
        self.size = 0

    def __str__(self):
        text = ''
        temp = self. head
        while temp:
            text += str(temp.data) + ' ' 
            temp = temp.next
        
        return text


    def append(self,data):
        if self.head == None:
            self.head = Node(data)
        else:
            temp = self.head
            while True:
                if temp.next == None:
                    break
                temp = temp.next
            temp.next = Node(data)
            temp.next.prev = temp
    def insert(self):
        pass
    def remobe(self):
        pass

    def pop(self):
        pass
a = DLL()
a.append(10)
print(a)
a.append(20)
print(a)