Yatzy Scoring trouble. No matter what I roll I get back zero points. Help please!

# File: dice.py
import random


class Die:
    def __init__(self, sides=2, value=0):
        if not sides >= 2:
            raise ValueError("Must have at least 2 sides")
        if not isinstance(sides, int):
            raise ValueError("Sides must be a whole number")
        self.value = value or random.randint(1, sides)

    def __int__(self):
        return self.value

    def __eq__(self, other):
        return int(self) == other

    def __ne__(self, other):
        return int(self) != other# Or:   return not int (self) == other

    def __gt__(self, other):
        return int(self) > other

    def __lt__(self, other):
        return int(self) < other

    def __ge__(self, other):
        return int(self) > other or int(self) == other#Or:    return int(self) >= other

    def __le__(self, other):
        return int(self) < other or int(self) == other#Or:    return int(self) <= other

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

    def __radd__(self, other):
        return int(self) + other# Or:   return self + other

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


class D6(Die):
    def __init__(self, value=0):
        super().__init__(sides=6, value=value)

# File: scoresheets.py
class YatzyScoresheet:
    def score_ones(self, hand):
        return sum(hand.ones)

    def score_twos(self, hand):
        return sum(hand.twos)

    def score_threes(self, hand):
        return sum(hand.threes)

    def score_fours(self, hand):
        return sum(hand.fours)

    def score_fives(self, hand):
        return sum(hand.fives)

    def score_sixes(self, hand):
        return sum(hand.sixes)

    def _score_set(self, hand, set_size):
        scores = [0]
        for worth, count in hand._sets.items():
            if count == set_size:
                scores.append(worth*set_size)
            return max(scores)

    def score_one_pair(self, hand):
        return self._score_set(hand, 2)

# File: hands.py
from dice import D6


class Hand(list):
    def __init__(self, size=0, die_class=None, *args, **kwargs):
        if not die_class:
            raise ValueError("You must provide a die class")
        super().__init__()

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

    def _by_value(self, value):
        dice = []
        for die in self:
            if die == value:
                dice.append(die)
        return dice


class YatzyHand(Hand):
    def __init__(self, *args, **kwargs):
        super().__init__(size=5, die_class=D6, *args, **kwargs)

    @property
    def ones(self):
        return self._by_value(1)

    @property
    def twos(self):
        return self._by_value(2)

    @property
    def threes(self):
        return self._by_value(3)

    @property
    def fours(self):
        return self._by_value(4)

    @property
    def fives(self):
        return self._by_value(5)

    @property
    def sixes(self):
        return self._by_value(6)

    @property
    def _sets(self):
        return {
            1: len(self.ones),
            2: len(self.twos),
            3: len(self.threes),
            4: len(self.fours),
            5: len(self.fives),
            6: len(self.sixes)
        }