def push_front(self, val):
newNode = ListNode(val, None)
if self._size == 0: #if list is empty, make element the head and tail
self._head = newNode
self._tail = newNode
newNode.set_next(
self._head) #new element's next now points to current head
self._head = newNode #update list's head
self._size += 1 #update list's size
def insert(self, index, val):
if index >= self._size or index < 0:
raise IndexError('Invalid index')
if index == 0:
self.push_front(val)
else:
newNode = ListNode(val, None)
item = self._head
for i in range(index -
1): #traverse list to find item at index - 1
item = item.get_next()
newNode.set_next(item.get_next())
item.set_next(newNode)
self._size += 1
