def load_rewards(tutor_name, data_dir):
    filename = os.path.join(data_dir, f'{tutor_name}_reward_logs.pkl')
    if (not os.path.exists(filename)):
        return {}
    with open(filename, 'rb') as f:
        return pickle.load(f)['rewards']
def load_rewards(tutor_name, data_dir):
    filename = os.path.join(data_dir, f'{tutor_name}_reward_logs.pkl')
    if (not os.path.exists(filename)):
        return {}
    with open(filename, 'rb') as f:
        return pickle.load(f)['rewards']