Searching in an unsorted binary tree

search.py

class Node(object):
  def __init__(self, value, left, right):
    self.value = value
    self.left = left
    self.right = right

def find(root, target):
  if root is None:
    return None
  if root.value == target:
    return root
  x = find(root.left, target)
  if x is not None:
    return x
  x = find(root.right, target)
  if x is not None:
    return x
  return None