Create a balanced binary search tree

[unozerocode]

Given a sorted list of numbers, change it into a balanced binary search tree. You can assume there will be no duplicate numbers in the list.

Here's a starting point:

from collections import deque

class Node:
def __init__(self, value, left=None, right=None):
    self.value = value
    self.left = left
    self.right = right

def __str__(self):
    # level-by-level pretty-printer
    nodes = deque([self])
    answer = ''
    while len(nodes):
    node = nodes.popleft()
    if not node:
        continue
    answer += str(node.value)
    nodes.append(node.left)
    nodes.append(node.right)
    return answer

def createBalancedBST(nums):
# Fill this in.

print createBalancedBST([1, 2, 3, 4, 5, 6, 7])
# 4261357
#   4
#  / \
# 2   6
#/ \ / \
#1 3 5 7