def insert_at(self, index, value):
'''
Inserts a value at the given position.
index -- the position as an int.
value -- an object.
'''
if not isinstance(index, int):
raise TypeError("index is not of type int")
if index < 0 or index > self.size:
raise LookupError("index out of bounds")
new_node = Node()
new_node.data = value
if self.head is None:
self.head = new_node
self.tail = new_node
self.size = 1
return
if index == 0:
new_node.next = self.head
self.head.previous = new_node
self.head = new_node
self.size = 1
else:
current_node = self.head
for i in range(index-1):
current_node = current_node.next
new_node.previous = current_node
new_node.next = current_node.next
current_node.next = new_node
if(new_node.next is None):
self.tail = new_node
self.size = 1
def append(self, value):
'''
Appends a new element to the Linked List at the end. If
the list is empty, then it´s added as both, head and tail nodes.
Arguments:
value -- an object to add.
'''
new_node = Node()
new_node.data = value
if(self.head is None):
self.head = new_node
self.tail = new_node
self.size = 1
return
self.size = 1
self.tail.next = new_node
new_node.previous = self.tail
self.tail = new_node