Need help debugging RPG roller

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):
        sides = 20
        super().__init__(sides)

class Hand(list):
    def __init__(self, size=0, die_class=None, *args, **kwargs):
        super().__init__()

        for _ in range(size):
            self.append(die_class())
        self.sort()

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

    @classmethod
    def roll(cls, num_dice=2):
        return cls(num_dice, die_class=D20)