RPG Roller 2/2 - why my code is not correct? the output seems legit...

import random


class Die:
    def __init__(self, sides=2):
        if sides < 2:
            raise ValueError("Can't have fewer than two sides")
        self.sides = sides
        self.value = random.randint(1, sides)

    def __int__(self):
        return self.value

    def __add__(self, other):
        return int(self) + other

    def __radd__(self, other):
        return self + other

class D20(Die):
    def __init__(self):
        super().__init__(sides=20)

from dice import D20

class Hand(list):
    def __init__(self, dice, *args, **kwargs):
        super().__init__(dice)

    @classmethod:
    def roll(cls, num):
        result = []
        for _ in range(num):
            result.append(D20())
        return cls(result)        

    @property
    def total(self):
        return sum(self)