请帮帮忙

class ScrollingCredits:

    def __init__(self):

        self.load_credits('assignment.txt')

        (self.background, self.background_rect) = \
            load_image('starfield.gif', True)

        self.font = pygame.font.Font(None, FONT_SIZE)

        self.scroll_speed = SCROLL_SPEED

        self.scroll_pause = SCROLL_PAUSE

        self.end_wait = END_WAIT

        self.reset()

        def load_credits(self, filename):

            f = open(filename)

            credits = []

            while 1:

                line = f.readline()

                if not line:

                    break

            line = string.rstrip(line)

            credits.append(line)

            f.close()

            self.lines = credits

我收到以下错误

line 66, in __init__
    self.load_credits('assignment.txt')
AttributeError: 'ScrollingCredits' object has no attribute 'load_credits'

我想知道它是否可能是assignmentidertxt，但我不是100%，我谷歌了一下，但我似乎找不到解决方案，帮助将非常感激