def adjust_meta_train_learning_rate(optimizer, epoch, args):
    """Adjust the learning rate according the epoch"""
    exp = epoch > args.schedule[4] and 5 or epoch > args.schedule[3] and 4 or epoch > args.schedule[2] and 3 or epoch > args.schedule[1] and 2 or epoch > args.schedule[0] and 1 or 0
    meta_train_lr = args.meta_train_lr * (args.gamma ** exp)
    #print('the lr for meta-train is: ', meta_train_lr)
    for param_group in optimizer.param_groups:
        param_group['lr'] = meta_train_lr
    
    return meta_train_lr