def update(self, val, n=1):
    for _ in range(n):
        self.correct = utils.reduce_lists(self.correct, val.correct)
        self.total = utils.reduce_lists(self.total, val.total)
        self.sys_len += val.sys_len
        self.ref_len += val.ref_len
def update(self, val, n=1):
    for _ in range(n):
        self.correct = utils.reduce_lists(self.correct, val.correct)
        self.total = utils.reduce_lists(self.total, val.total)
        self.sys_len += val.sys_len
        self.ref_len += val.ref_len