Help with Object-Oriented Python challenge task

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

    def __repr__(self):
        return str(self.value)

    def __len__(self):
        return len(self)


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

from dice import D20

class Hand(list):
    def roll(self, size=0):
        for num in range(size):
            self.append((dice.D20))
        return self

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