You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: tournament.rs
    path of file: ./repos/SquireCore/squire_lib/src
    
    the code of the file until where you have to start completion: use std::{
    collections::HashMap,
    fmt::{Display, Write},
    time::Duration,
};

use chrono::{DateTime, Utc};
use itertools::Itertools;
use serde::{Deserialize, Serialize};
use serde_with::{serde_as, Seq};
use uuid::Uuid;

pub use crate::identifiers::{TournamentId, TournamentIdentifier};
use crate::{
    accounts::SquireAccount,
    admin::{Admin, Judge, TournOfficialId},
    error::TournamentError,
    identifiers::{AdminId, JudgeId, PlayerId, PlayerIdentifier, RoundId, RoundIdentifier},
    operations::{AdminOp, JudgeOp, OpData, OpResult, PlayerOp, TournOp},
    pairings::{PairingStyle, PairingSystem, Pairings},
    players::{Deck, Player, PlayerRegistry, PlayerStatus},
    rounds::{Round, RoundRegistry, RoundResult, RoundStatus},
    scoring::{ScoringSystem, StandardScore, Standings},
    settings::{GeneralSettingsTree, SettingsTree, TournamentSetting, TournamentSettingsTree},
};

#[derive(Serialize, De
    
    fn players_in_paired_rounds() {
        let mut tourn =
            Tournament::from_preset("Test".into(), TournamentPreset::Swiss, "Test".into());
        assert_eq!(tourn.pairing_sys.common.match_size, 2);
        let acc = spoof_account();
        let admin = Admin::new(acc);
        tourn.admins.insert(admin.id, admin.clone());
        let acc = spoof_account();
        tourn
            .apply_op(Utc::now(), TournOp::RegisterPlayer(acc, None))
            .unwrap()
            .assume_register_player();
        let acc = spoof_account();
        tourn
            .apply_op(Utc::now(), TournOp::RegisterPlayer(acc, None))
            .unwrap()
            .assume_register_player();
        tourn
            .apply_op(Utc::now(), TournOp::AdminOp(admin.id, AdminOp::Start))
            .unwrap()
            .assume_nothing();
        let pairings = tourn.create_pairings().unwrap();
        let r_ids = tourn
            .apply_op(
                Utc::now(),
                TournOp::AdminOp(admin.id, AdminOp::PairRound(pairings)),
            )
            .unwrap()
            .assume_pair();
        assert_eq!(r_ids.len(), 1);
        let rnd = tourn.get_round_by_id(&r_ids[0]).unwrap();
        assert_eq!(rnd.players.len(), 2);
    }