在类中使用return时出现语法错误

Question

任何人都可以解释为什么我在return方法中收到has_happened()语句的语法错误。

from sys import argv
import time
from datetime import date


class Game(object):

    def __init__(self, home, away, home_odds, away_odds, date):
        self.home = home
        self.away = away
        self.home_odds_str = home_odds
        self.away_odds_str = away_odds
        self.date = date

    def to_string(self):
        return self.home + ", " + self.away + ", " + self.home_odds + ", " + self.away_odds + ", " + self.result + ", " + self.date

    def has_happened(self):
        dates_split = self.date.split("/")
        today = date.today()
        game_date = date(int(dates_split[2]), int(dates_split[1]), int(dates_split[0])
        return str(game_date < today)


game1 = Game("t1", "t2", "7/8", "9/1", "29/9/2016")
game1.has_happened()

Answer 1

def has_happened(self):
    dates_split = self.date.split("/")
    today = date.today()
    game_date = date(int(dates_split[2]), int(dates_split[1]), int(dates_split[0]))
    return str(game_date < today)