Hi, here's your problem today. This problem was recently asked by Apple:

You are given two singly linked lists. The lists intersect at some node. Find, and return the node. Note: the lists are non-cyclical.

Example:

```
A = 1 -> 2 -> 3 -> 4
B = 6 -> 3 -> 4
```

This should return 3 (you may assume that any nodes with the same value are the same node).

Here is a starting point:

```
def intersection(a, b):
# fill this in.
class Node(object):
def __init__(self, val):
self.val = val
self.next = None
def prettyPrint(self):
c = self
while c:
print c.val,
c = c.next
a = Node(1)
a.next = Node(2)
a.next.next = Node(3)
a.next.next.next = Node(4)
b = Node(6)
b.next = a.next.next
c = intersection(a, b)
c.prettyPrint()
# 3 4
```