Binary Tree Implementation with list of list in Python

__author__ = 'nitin'

def BinaryTree(r):
    return [r, [], []]

def insertLeft(root,newBranch):
    t = root.pop(1)
    if len(t) > 1:
        root.insert(1,[newBranch,t,[]])
    else:
        root.insert(1,[newBranch, [], []])
    return root

def insertRight(root,newBranch):
    t = root.pop(2)
    if len(t) > 1:
        root.insert(2,[newBranch,[],t])
    else:
        root.insert(2,[newBranch,[],[]])
    return root

def getRootVal(root):
    return root[0]

def setRootVal(root,newVal):
    root[0] = newVal

def getLeftChild(root):
    return root[1]

def getRightChild(root):
    return root[2]

r = BinaryTree(3)
insertLeft(r,4)
insertLeft(r,5)
insertRight(r,9)
insertRight(r,7)
l = getLeftChild(r)
print(l)

setRootVal(l,9)
print(r)
insertLeft(l,11)
print(r)
print(getRightChild(getRightChild(r)))