import tkinter as tk
window = tk.Tk()
canvas = tk.Canvas(window, width=400, height=400, bg='yellow')
canvas.create_arc(10, 100, 380, 300, outline='red', width=5)
canvas.create_arc(10, 100, 380, 300, outline='blue', width=5,
style=tk.CHORD, start=90, fill='white')
canvas.create_arc(10, 100, 380, 300, outline='green', width=5,
style=tk.ARC, start=180, extent=180)
button = tk.Button(window, text="Quit", command=window.destroy)
canvas.grid(row=0)
button.grid(row=1)
window.mainloop()
这段代码显示不出output,不知道问题出在哪里
还有start的度数是怎么样计算的
```