Python tree traversals - inorder, preorder, postorder

tree-orders.py

def inorder(node):
 
	if node.left != None:
		inorder(node.left)
 
	print node.cargo
 
	if node.right != None:
		inorder(node.right)
 
def preorder(node):
 
	print node.cargo
 
	if node.left != None:
		preorder(node.left)
 
	if node.right != None:
		preorder(node.right)
 
def postorder(node):
	if node.left != None:
		postorder(node.left)
	
	if node.right != None:
		postorder(node.right)
 
	print node.cargo