Нужна помощь в отладке футбольного симулятора |AttributeError: у объекта 'NoneType' нет атрибута 'skill'

Question

Вывод этого скрипта должен имитировать матч между 6 футбольными командами, играющими в 10 матчей, отображать общий рейтинг навыков для этой команды и отображать победителя в каждой игре.

Пример:Аресенал 666 против Манчестер Сити 650Игра начинаетсяИгра заканчивается Aresenal 666 побед

Однако при запуске кода в среде IDE появляется следующая ошибка:

Сезон начинаетсяРаунд начинается'<' team.Team объект в 0x006C0EF0> vs. '<' team.Team объект в 0x006C0F30>Игра начинаетсяИгра заканчиваетсяTraceback (последний вызов был последним):Файл «C: / Users / --- / Desktop / Python / main.py», строка 47, в модуле «<»>главный()Файл "C: / Users / --- / Desktop / Python / main.py", строка 40, в основномfirst_league.play_season ()Файл "C: \ Users --- \ Desktop \ Python \ team.py", строка 88, в play_seasonself.play_round ()Файл "C: \ Users --- \ Desktop \ Python \ team.py", строка 108, в play_roundgame.play ()Файл "C: \ Users --- \ Desktop \ Python \ team.py", строка 62, в игреif self.home_team.rating ()> self.away_team.rating ():Файл "C: \ Users --- \ Desktop \ Python \ team.py", строка 25, в рейтингерейтинг + = player.skillAttributeError: у объекта 'NoneType' нет атрибута 'skill'

Есть идеи, как это исправить?

main.py

import random
from player import generate_player
from team import League, Team

    def generate_player():
        pass


    def main():
        #set up our data
        #generate some players
        players = []
        for i in range (100):
            players.append(generate_player())



        #set up 6 teams
        teams = [
            Team('Chelsea'),
            Team('Man City'),
            Team('Arsenal'),
            Team('West Ham'),
            Team('Hull City'),
            Team('Swansea'),
        ]

        for team in teams:
            for player_num in range(11):
                #give them 11 starting players
                selected_player = random.choice(players)
                team.players.append(selected_player)
                players.remove(selected_player)

        #we have a single league
        first_league = League('Premiership League')
        first_league.set_teams(teams)

        first_league.play_season()



        print('a')

    if __name__ == '__main__':
        main()

player.py

import random

class Players:
    """
    player is on a single team, with many other players
    players play in a game for a team
    """
    def __init__(self, name):
        self.name = name

        #player skill rankings
        self.skill = skill

def salary(self):   
    return 50000 + self.skill * 100



def generate_player():
    first_names = [
        'Sophia', 'Jackson', 'Emma', 'Aiden', 'Olivia', 'Lucas', 'Ava', 'Liam', 'Mia', 'Noah', 'Isabella', 'Ethan',
        'Riley', 'Mason', 'Aria', 'Caden', 'Zoe', 'Oliver', 'Charlotte', 'Elijah', 'Lily', 'Grayson', 'Layla', 'Jacob',
        'Amelia', 'Michael', 'Emily', 'Benjamin', 'Madelyn', 'Carter', 'Aubrey', 'James', 'Adalyn', 'Jayden',
        'Madison', 'Logan', 'Chloe', 'Alexander',   
    ]
    first_name = random.choice(first_names)
    last_name = random.choice(last_name)

    full_name = '{} {}'.format(first_name, last_name)
    # generate skill and salary
    skill = 10 + random.randint(0, 90)

    return Player(full_name, skill)

team.py

import copy
import random


class Team:
    """
    Team has many players
    Team has a ranking in a league
    Team plays games against other teams
    Team has a single manager
    """
    def __init__(self,name):
        self.name = name
        self.players = []

        self.wins = 0
        self.losses = 0

    def rating(self):
        """
        what is the rating of the team
        """
        rating = 0
        for player in self.players:
            rating += player.skill

        return rating

def __str__(self):
        return '{} {}'.format(self.name, self.rating())

class Manager:
    """
    runs a teams
    """
    pass

class Game:
    """
    plays a game between two teams
    game belongs to a league
    """
    def __init__(self, league, home_team, away_team):
        self.league = league
        self.home_team = home_team
        self.away_team = away_team

        self.home_team_won = None

        print('{}  vs. {}'.format(self.home_team, self.away_team))


    def play(self):
        """
        play the game, return who won
        True means the home team won, False means the away team won
        """
        print ('Play begins')
        #insert game here

        print ('Play ends')
        if self.home_team.rating() > self.away_team.rating():
            print ('{} wins'.format(self.home_team))
            self.home_team_won = True
        else:
            print('{} wins.'.format(self.away_team))
            self.home_team_won = False


class League:
    """
    league has many teams
    each team is going to have a ranking within this league
    """
    def __init__(self, name):
        self.name = name
        self.teams = []

    def set_teams(self, teams):
        self.teams = teams

    def play_season(self):
        """
        play 10 games between all the teams
        """
        print ('Season begins')
        for i in range(10):
            self.play_round()
        print('Season ends')

    def play_round(self):
        """
        play a round, which is 3 games
        """
        print('Round begins')
        num_teams = len(self.teams)
        num_games = num_teams // 2

        teams_to_play = copy.copy(self.teams)

        for game_num in range(num_games):
            home_team = random.choice(teams_to_play)
            teams_to_play.remove(home_team)
            away_team = random.choice(teams_to_play)
            teams_to_play.remove(away_team)

            game = Game(self, home_team, away_team)
            game.play()
            self.resolve_game(game)


        print('Round ends')

        #ladder status
        self.ladder()

    def ladder(self):
        for team in sorted(self.teams, key= lambda t: t.wins):
            print('{} {} wins'.format(team, team.wins))

    def resolve_game(self, game):
        if game.home_team_won:
            # home team won
            game.home_team.wins += 1
            game.away_team.losses += 1

        else:
            #away team won
            game.away_team.wins += 1
            game.home_team.losses += 1