def findFinger(node, key):
    current=node
    for x in range(k):
        if distance(current.id, key) > \
           distance(node.finger[x].id, key):
            current=node.finger[x]
    return current

def lookup(start, key):
    current=findFinger(start, key)
    next=findFinger(current, key)
    while distance(current.id, key) > \
          distance(next.id, key):
        current=next
        next=findFinger(current, key)
    return current