in order tree traversal iterator

inorderiterator.py

class InOrderTree(Tree):
    """ iterator for inorder traversal over a binary tree """
    def __init__(self, root):
        self.node = root
        self.stack = []
    
    def __iter__(self):
        return self
        
    def next(self):
        if self.stack or self.node:
            if self.node:
                self.stack.append(self.node)
                self.node = self.node.left
            else:
                curr = self.stack.pop()
                self.node = curr.right
                return curr
        else:
            raise StopIteration