if prevX == None:
head = currY
else:
prevX.next = currY
# If y is head // make x as the new head
if prevY == None:
head = currX
else:
prevY.next = currX
# Swap next pointers
temp = currX.next
currX.next = currY.next
currY.next = temp
return head
if __name__ == '__main__':
l = LinkedList()
l.append_node("A")
l.append_node("B")
l.append_node("C")
l.append_node("D")
l.traverse()
l.head = swap_node(l.head, 'A', 'C')
l.traverse()
