tkinter error?

Question

Python

I am writing my text editor and wanted to make tabs but got an error:
Traceback (most recent call last):
File "C:\Users\User\Downloads\Tornado\main.py", line 35, in
nb = Notebook()
NameError : name 'Notebook' is not defined

Code (not all):

import tkinter as tk
from tkinter import *
import tkinter.ttk as ttk
from tkinter import filedialog
from tkinter import messagebox

import os
from hashlib import md5
from pygments.lexers import PythonLexer
from tokens import token_type_to_tag

lexer = PythonLexer()


class Document:
    def __init__(self, Frame, TextWidget, FileDir=''):
        self.file_dir = FileDir
        self.file_name = 'Untitled'if not FileDir else os.path.basename(FileDir)
        self.text = TextWidget
        self.status = md5(self.text.get(1.0, 'end').encode('utf-8'))


app = Tk()
app.title("Tornado")
app.iconbitmap("tornado.ico")
app.geometry("1260x600")

frame = Frame(app)
frame.pack()

filetypes = (("Normal text file", "*.txt"), ("All files", "*.*"))
init_dir = os.path.join(os.path.expanduser('~'), 'Desktop')
tabs = {}

nb = Notebook()
nb.bind("<Button-2>", close_tab)
nb.bind("<B1-Motion>", move_tab)
nb.pack(expand=1, fill="both")
nb.enable_traversal()
app.protocol('WM_DELETE_WINDOW', exit)
notebook.bind("<<NotebookTabChanged>>", select_tab)

Answer 1

In this particular piece of code, the Notebook class is not initialized. If it is written in another file, you need from "" import Notebook.