Trouble With Bubble Blaster Python Code?
<p>I am working on a project, and have completed the code, yet one error is still showing up, even though I am sure my code is correct.</p>

<p>Here is the error that keeps showing up:</p>

<pre><code>Traceback (most recent call last):
  File "C:\Python33\bubblee blaster.py", line 61, in &lt;module&gt;
    clean_up_bubs()
NameError: name 'clean_up_bubs' is not defined
</code></pre>

<p>Here is my python code:</p>

<pre><code>from tkinter import *
HEIGHT = 500
WIDTH = 800
window = Tk()
window.title('bubble blaster')
c = Canvas(window, width=WIDTH, height=HEIGHT, bg='darkblue')
c.pack()
ship_id = c.create_polygon(5, 5, 5, 25, 30, 15, fill='red')
ship_id2 = c.create_oval(0, 0, 30, 30, outline='red')
SHIP_R = 15
MID_X = WIDTH / 2
MID_Y = HEIGHT / 2
c.move(ship_id, MID_X, MID_Y)
c.move(ship_id2, MID_X, MID_Y)
SHIP_SPD = 10
def move_ship(event):
    if event.keysym == 'Up':
        c.move(ship_id, 0, -SHIP_SPD)
        c.move(ship_id2, 0, -SHIP_SPD)
    elif event. keysym == 'Down':
        c.move(ship_id, 0, SHIP_SPD)
        c.move(ship_id2, 0, SHIP_SPD)
    elif event.keysym == 'Left':
        c.move(ship_id, -SHIP_SPD, 0)
        c.move(ship_id2, -SHIP_SPD, 0)
    elif event.keysym == 'Right':
        c.move(ship_id, SHIP_SPD, 0)
        c.move(ship_id2, SHIP_SPD, 0)
c.bind_all('&lt;Key&gt;' , move_ship)
from random import randint
bub_id = list()
bub_r = list()
bub_speed = list()
MIN_BUB_R = 10
MAX_BUB_R = 30
MAX_BUB_SPD = 110
GAP = 100
def create_bubble():
    x = WIDTH + GAP
    y = randint(0, HEIGHT)
    r = randint(MIN_BUB_R, MAX_BUB_R)
    id1 = c.create_oval(x - r, y - r, x +  r, y + r, outline='white')
    bub_id.append(id1)
    bub_r.append(r)
    bub_speed.append(randint(1, MAX_BUB_SPD))
def move_bubbles():
    for i in range(len(bub_id)):
        c.move(bub_id[i], -bub_speed[i], 0)
from time import sleep, time
BUB_CHANCE = 10
TIME_LIMIT = 30
BONUS_SCORE = 1000
score = 0
bonus = 0
end = time() + TIME_LIMIT
#MAIN GAME LOOP
while time() &lt; end:
    if randint(1, BUB_CHANCE) == 1:
        create_bubble()
        move_bubbles()
        clean_up_bubs()
        score += collision()
        if (int(score / BONUS_SCORE)) &gt; bonus:
            bonus += 1
            end += TIME_LIMIT
            show_score(score)
            show_time(int(end - time()))
        print(score)
        window.update()
        sleep(0.01)
def get_coords(id_num):
    pos = c.coords(id_num)
    x = (pos[0] + pos[2])/2
    y = (pos[1] + pos[3])/2
    return x, y
def del_bubble(i):
    del bub_r[i]
    del bub_speed[i]
    c.delete(bub_id[i])
    del bub_id[i]
def clean_up_bubs():
   for i in range(len(bub_id)-1, -1, -1):
       x, y = get_coords(bub_id[i])
       if x &lt; -GAP:
          del_bubble(i)
from math import sqrt
def distance(id1, id2):
    x1, y1 = get_coords(id1)
    x2, y2 = get_coords(id2)
    return sqrt((x2 - x1)**2 + (y2 - y1)**2)
def collision():
    points = 0
    for bub in range(len(bub_id)-1, -1, -1):
        if distance(ship_id2, bub_id[bub]) &lt; (SHIP_R + bub_r[bub]):
            points += (bub_r[bub] + bub_speed[bub])
            del_bubble(bub)
    return points
c.create_text(50, 30, text='TIME' , fill='white' )
c.create_text(150, 30, text='SCORE' , fill='white' )
time_text = c.create_text(50, 50, fill='white' )
score_text = c.create_text(150, 50, fill='white' )
def show_score(score):
    c.itemconfig(score_text, text=str(score))
def show_time(time_left):
    c.itemconfig(time_text, text=str(time_left))
c.create_text(MID_X, MID_Y, \
     text='GAME OVER', fill='white', font=('Helvetica' ,30))
c.create_text(MID_X, MID_Y + 30, \
              text='Score: '+ str(score), fill='white')
c.create_text(MID_X, MID_Y + 45, \
              text='Bonus time: '+ str(bonus*TIME_LIMIT), fill='white')
</code></pre>