def insertIndent():
            if self.useTabs:
                cursor.insertText('\t')
            else:  # indent to integer count of indents from line start
                charsToInsert = self.width - (len(self._qpart.textBeforeCursor()) % self.width)
                cursor.insertText(' ' * charsToInsert)
def dfs_print(root):
        if root is None:
            return
        dfs_print(root.left)
        print(str(root.key) + ' ', end='')
        dfs_print(root.right)