tree_class.py

class BinaryTree:
	def __init__(self,rootObj):
		self.key = rootObj
		self.leftChild = None
		self.rightChild = None

	def __repr__(self):
		return self.key

	def insertLeft(self, newNode):
		if self.leftChild == None:
			self.leftChild = BinaryTree(newNode)
		else:
			t = BinaryTree(newNode)
			t.leftChild = self.leftChild
			self.leftChild = t

	def insertRight(self, newNode):
		if self.rightChild == None:
			self.rightChild = BinaryTree(newNode)
		else:
			t = BinaryTree(newNode)
			t.rightChild = self.rightChild
			self.rightChild = t

	def getRightChild(self):
		return self.rightChild

	def getLeftChild(self):
		return self.leftChild

	def setRootVal(self,obj):
		self.key = obj

	def getRootVal(self):
		return self.key

def preorder(tree):
    if tree:
        print(tree.getRootVal())
        preorder(tree.getLeftChild())
        preorder(tree.getRightChild())

def postorder(tree):
    if tree:
        postorder(tree.getLeftChild())
        postorder(tree.getRightChild())
        print(tree.getRootVal())

r = BinaryTree('a')
print(r.getRootVal())
print(r.getLeftChild())
r.insertLeft('b')
print(r.getLeftChild())
print(r.getLeftChild().getRootVal())
r.insertRight('c')
print(r.getRightChild())
print(r.getRightChild().getRootVal())
r.getRightChild().setRootVal('hello')
print(r.getRightChild().getRootVal())
print()
preorder(r)
print()
postorder(r)