python - Tkinter ダイスローラー

Question

私はプログラミングが初めてで、Tkinter を使用して Python でサイコロ ローラーを作成する割り当てが設定されたばかりです。私はこのエラーメッセージに完全に困惑しています:

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Python27\lib\lib-tk\Tkinter.py", line 1470, in __call__
    return self.func(*args)
  File "C:/Users/d/Desktop/Dice Simulator/Simulator.py", line 12, in roll
    if y == 1:
UnboundLocalError: local variable 'y' referenced before assignment

誰かが私の間違いに光を当てることができますか? ここに私のコード全体があります：

y = 1
print "Please wait for the GUI to load"
from Tkinter import *
DICE = dict(
    sixsided={'name': 'Six Sided Dice',
              'side': 6},
    eightsided = {'name': 'Eight Sided Dice',
                  'side': 8}
    )
names = ['Six Sided Dice', 'Eight Sided Dice']
import random


def back_():
    diceroll.destroy()

def roll():
    if y == 1:
        blankanswer.pack_forget()
        droll.set("You rolled a " + str(random.randrange(1,endnum,1)))
        filledanswer.pack()
        y = 2
    if y == 2:
        droll.set("You rolled a " + str(random.randrange(1,endnum,1)))

def cont_():
    y = 1
    if dice.get() == "Six Sided Dice":
        selecteddice = "sixsided"
    if dice.get() == "Eight Sided Dice":
        selecteddice = "eightsided"

    diceroll = Tk()
    diceroll.title("Dice Simulator")

    endnum = int(DICE[selecteddice]["side"])

    droll = StringVar()
    droll.set("You rolled a " + str(random.randrange(1,endnum,1)))

    reroll = Button(diceroll, text="Click to roll the " + dice.get() + ".",command=roll)
    reroll.pack()

    blankanswer = Label(diceroll, text="You rolled a  ")
    blankanswer.pack()


    filledanswer = Label(diceroll, textvariable=droll)

    back = Button(diceroll, text="Back", command=back_)
    back.pack(side=BOTTOM)

    diceroll.mainloop()



diceselect = Tk()
diceselect.title("Select your dice")

Label(diceselect, text="Please select the dice you would like to roll").pack()

dice = StringVar()
dice.set("Six Sided Dice")

entry = OptionMenu(diceselect, dice, *names)
entry.configure(width=15)
entry.pack(side=LEFT)

cont = Button(diceselect, text="Continue", command=cont_)
cont.configure(width=15)
cont.pack(side=RIGHT)

diceselect.mainloop()

前もって感謝します！