This script generates the circle system schedule

circle.py

def circle(*players):
    '''
    you can find the description here https://safoyeth.com/2017/03/04/chessscripts/
    '''
    if isinstance(players, tuple):
        players = list(players)
    if not len(players) % 2 == 0:
        players.append(None)
    result = [[["", ""] for _ in range(int(len(players)/2))] for i in range(int(len(players)-1))]
    for each in result:
        if result.index(each) % 2 == 0:
            each[0][1] = players[-1]
        else:
            each[0][0] = players[-1]
    i = 0
    for tour in result:
        for game in tour:
            if game[0] == "":
                game[0] = players[i]
                if i < len(players)-2:
                    i += 1
                else:
                    i = 0
            else:
                game[1] = players[i]
                if i < len(players)-2:
                    i += 1
                else:
                    i = 0
    players.pop(-1)
    i = len(players)-1
    for tour in result:
        for game in tour:
            if game[0] == "":
                if not game[1] == players[i]:
                    game[0] = players[i]
                    if i >= 1:
                        i -= 1
                    else:
                        i = len(players) - 1
            if game[1] == "":
                if not game[0] == players[i]:
                    game[1] = players[i]
                    if i >= 1:
                        i -= 1
                    else:
                        i = len(players) - 1
    return tuple(result)