input: 
  class Node:
      def __init__(self, data):
          self.data = data
          self.next = None
          self.prev = None
  
  
  class DoubleLinkedList:
      def __init__(self): 
          self.head = None
   
      def append(self, new_data): 
          new_node = Node(new_data) 
          if self.head is None:
              self.head =  new_node
          else: 
              curr_node = self.head
              while curr_node.next != None:
                  curr_node = curr_node.next
              curr_node.next = new_node
              new_node.prev = curr_node
   
      def prepend(self, new_data):
          new_node = Node(new_data) 
          if self.head is None: 
              self.head = new_node
              return
          new_node.next = self.head
          self.head.prev = new_node 
          self.head = new_node
  
      def reverse(self):
          curr_node = self.head
          while curr_node:
              temp = curr_node.next
              curr_node.next = curr_node.prev
              curr_node.prev = temp
              curr_node = curr_node.prev
          if temp:
              self.head = temp.prev
  
  # Example usage:
  # >>> dll = DoubleLinkedList()
  # >>> dll.append(1)
  # >>> dll.append(2)
  # >>> dll.append(3)
  # >>> dll.prepend(0)
  # >>> dll.reverse()
  # The list will be [3, 2, 1, 0] after reversal.
  
output:     
      def delete(self, key):
          curr_node = self.head
          while curr_node:
              if curr_node.data == key:
                  if curr_node.prev:
                      curr_node.prev.next = curr_node.next
                  else:
                      self.head = curr_node.next
                  if curr_node.next:
                      curr_node.next.prev = curr_node.prev
                  return
              curr_node = curr_node.next
  
      def print_list(self):
          curr_node = self.head
          while curr_node:
              print(curr_node.data, end=" ")
              curr_node = curr_node.next
          print()
  