def build_simple_tree():
 node = TreeNode(1)
 node.left = TreeNode(2)
 node.right = TreeNode(3)
 node.right.left = TreeNode(4)
 node.right.right = TreeNode(5)
 return node

def build_simple_tree ( ) : node = TreeNode ( 1 ) node . left = TreeNode ( 2 ) node . right = TreeNode ( 3 ) node . right . left = TreeNode ( 4 ) node . right . right = TreeNode ( 5 ) return node
create a simple tree .