tree.py

class Tree(object):
    def __init__(self, root):
        self.root = root


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


def main():
    tree = Tree(Node("i am root", left=Node("left child"), right=Node("right child")))
    print tree.root.left.value

if __name__ == '__main__':
    main()