BinaryTree implementation using Python lists

BinaryTree_Lists

"""
BinaryTree code using Python Lists

[5, [4, [], []], []]
[3, [9, [4, [], []], []], [7, [], [6, [], []]]]
[3, [9, [11, [4, [], []], []], []], [7, [], [6, [], []]]]
[6, [], []]
"""

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

def insertLeft(root, newBranch):
    left_child = getLeftChild(root)
    set_left_child(root, [newBranch, left_child, []])
    return root

def insertRight(root, newBranch):
    right_child = getRightChild(root)
    set_right_child(root, [newBranch, [], right_child])
    return root

def getRootVal(root):
    return root[0]

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

def set_right_child(root, branch):
    root[2] = branch

def set_left_child(root, branch):
    root[1] = branch

def getLeftChild(root):
    return root[1]

def getRightChild(root):
    return root[2]

r = BinaryTree(3)
insertLeft(r,4)
insertLeft(r,5)
insertRight(r,6)
insertRight(r,7)
l = getLeftChild(r)
print(l)

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