迷路の画像の表示がうまくいかない

Python3.6.3を使っています
pythonの本に載っていたスクリプトで迷路を作ろうというものが出てきたのですが
どうもうまくいきません

python
1data=[
2	[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],
3	[1,2,0,0,1,0,0,0,1,0,0,1,0,0,0,1,0,0,1],
4	[1,0,1,0,1,1,1,0,0,0,0,0,0,1,0,0,0,1,1],
5	[1,0,1,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,1],
6	[1,0,1,0,0,0,1,0,0,0,0,1,0,1,0,1,0,0,1],
7        [1,0,0,0,1,1,1,1,1,1,0,1,0,0,0,0,1,1,1],
8        [1,0,1,0,1,0,0,1,0,0,0,1,0,0,1,0,0,0,1],
9        [1,0,1,0,0,1,1,1,0,1,0,1,0,1,1,0,1,1,1],
10        [1,0,1,0,1,0,0,0,0,1,0,0,0,1,0,0,0,3,1],
11        [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]
12]
13

まずこれをmaze_dataという名前で保存した後

python
1from tkinter import *
2
3tile_size=20
4
5def load_map_data():
6    from maze_data import data
7    return data
8
9
10def draw_map(cv,data):
11    rows=len(data)
12    cols=len(data[0])
13    for y in range(rows):
14        y1=y*tile_size
15        y2=y1+tile_size
16
17        for x in range(cols):
18            x1=x*tile_size
19            x2=x1+tile_size
20
21            p=data[y][x]
22
23            if p==0:color="white"
24            if p==1:color="#404040"
25            if p==2:color="red"
26            if p==3:color="blue"
27
28            cv.create_rectangle(
29                x1,y1,x2,y2,
30                fill=color,
31                outline="black",width=2)
32
33def create_window(map_data,events=[]):
34    win=Tk()
35    win.title("迷路")
36    rows=len(map_data)
37    cols=len(map_data[0])
38    cv=Canvas(win,
39              width=(cols*tile_size),
40              height=(rows*tile_size))
41    cv.pack()
42    draw_map(cv.map_data)
43
44    for func in events: func(cv.map_data)
45    win.mainloop()
46
47if __name__=="__main__":
48    map_data=load_map_data()
49    create_window(map_data)
50

をIDLE(シェル?)で実行しました
その結果
RESTART: C:\Users\user\AppData\Local\Programs\Python\Python36-32\maze_show.py
Traceback (most recent call last):
File "C:\Users\user\AppData\Local\Programs\Python\Python36-32\maze_show.py", line 49, in <module>
create_window(map_data)
File "C:\Users\user\AppData\Local\Programs\Python\Python36-32\maze_show.py", line 42, in create_window
draw_map(cv.map_data)
AttributeError: 'Canvas' object has no attribute 'map_data'