def text(self):
        """Get indent text as \t or string of spaces
        """
        if self.useTabs:
            return '\t'
        else:
            return ' ' * self.width
def dfs_print(root):
        if root is None:
            return
        dfs_print(root.left)
        print(str(root.key) + ' ', end='')
        dfs_print(root.right)