How to use the pubsub-js.publishSync function in pubsub-js

aEvent.preventDefault();
                    }
                    break;

                case 83: // S
                    if ( hasOption ) {
                        Pubsub.publishSync( Messages.SAVE_SONG );
                        aEvent.preventDefault();
                    }
                    break;

                case 86: // V

                    // paste current selection
                    if ( hasOption ) {
                        Pubsub.publishSync(
                            Messages.SAVE_STATE,
                            StateFactory.getAction( States.PASTE_SELECTION, {
                                efflux: efflux,
                                updateHandler: () => Pubsub.publishSync( Messages.REFRESH_PATTERN_VIEW )
                            })
                        );
                    }
                    break;

                case 88: // X

                    // cut current selection

                    if ( hasOption )
                    {
                        Pubsub.publishSync(

function handleBroadcast( type, payload )
{
    switch ( type )
    {
        case Messages.LOAD_SONG:

            const song = ( typeof payload === "string" ) ? efflux.SongModel.getSongById( payload ) : payload;

            if ( song && song.meta && song.patterns ) {

                efflux.activeSong = ObjectUtil.clone( song );
                efflux.EditorModel.reset();
                efflux.EditorModel.amountOfSteps = song.patterns[ 0 ].steps;
                SongUtil.resetPlayState( efflux.activeSong.patterns ); // ensures saved song hasn't got "frozen" events
                Pubsub.publishSync( Messages.SONG_LOADED, song );
                Pubsub.publishSync( Messages.CREATE_LINKED_LISTS );
                efflux.StateModel.flush();
            }
            break;

        case Messages.TRANSFORM_LEGACY_SONG:

            if ( typeof payload === "object" )
                SongValidator.transformLegacy( payload );
            break;

        case Messages.CREATE_LINKED_LISTS:
            EventUtil.linkEvents( efflux.activeSong.patterns, efflux.eventList );
            break;

        case Messages.SAVE_STATE:

{
        currentStep = 0;

        // advance the measure if the Sequencer wasn't looping

        if ( !looping && ++currentMeasure === totalMeasures )
        {
            // last measure reached, jump back to first
            currentMeasure = 0;

            // stop playing if we're recording and looping is disabled

            if ( recording && !efflux.EditorModel.loopedRecording )
            {
                SequencerController.setPlaying( false );
                Pubsub.publishSync( Messages.RECORDING_COMPLETE );
                return;
            }
        }
        SequencerController.setPosition( currentMeasure, nextNoteTime );

        if ( recording )
        {
            // one bar metronome count in ?

            if ( Metronome.countIn && !Metronome.countInComplete ) {

                Metronome.enabled         = Metronome.restore;
                Metronome.countInComplete = true;

                currentMeasure        = 0;   // now we're actually starting!
                firstMeasureStartTime = audioContext.currentTime;

function handleMouseOver( aEvent )
{
    Pubsub.publishSync( Messages.DISPLAY_HELP, "helpTopicSong" );
}

function handleDelayChange( aEvent ) {

    const delay = model.instrumentRef.delay;

    delay.enabled  = ( Form.getSelectedOption( delayEnabledSelect ) === "true" );
    delay.type     = parseFloat( Form.getSelectedOption( delayTypeSelect ));
    delay.time     = parseFloat( delayTimeControl.value );
    delay.feedback = parseFloat( delayFeedbackControl.value );
    delay.cutoff   = parseFloat( delayCutoffControl.value );
    delay.offset   = parseFloat( delayOffsetControl.value ) - 0.5;

    Pubsub.publishSync( Messages.UPDATE_DELAY_SETTINGS, [ model.instrumentId, delay ]);
    invalidatePresetName();
}

function switchPattern( newMeasure )
{
    if ( editorModel.activePattern === newMeasure )
        return;

    currentMeasure = editorModel.activePattern = newMeasure;
    Pubsub.publishSync( Messages.PATTERN_SWITCH, newMeasure );

    const newSteps = efflux.activeSong.patterns[ newMeasure ].steps;
    if ( editorModel.amountOfSteps !== newSteps ) {
        editorModel.amountOfSteps = newSteps;
        Pubsub.publish( Messages.PATTERN_STEPS_UPDATED, newSteps );
    }
}

songs.forEach(( song ) =>
    {
        li = document.createElement( "li" );
        li.setAttribute( "data-id", song.id );
        li.innerHTML = "<span class="title">" + song.meta.title + ", by " + song.meta.author + "</span>" +
            "<span class="date">" + Time.timestampToDate( song.meta.modified ) + "</span>" +
            "<span class="delete">x</span>";

        list.appendChild( li );

        handler.addEventListener( li, "click", handleSongOpenClick );
        handler.addEventListener( li.querySelector( ".delete" ), "click", handleSongDeleteClick );
    });

    Pubsub.publishSync( Messages.CLOSE_OVERLAYS, SongBrowserController );
    Pubsub.publishSync( Messages.SHOW_BLIND );
    container.classList.add( "active" );
}

function handlePatternClear( aEvent )
{
    efflux.activeSong.patterns[ editorModel.activePattern ] = PatternFactory.createEmptyPattern( editorModel.amountOfSteps );
    selectionModel.clearSelection();
    Pubsub.publishSync( Messages.REFRESH_PATTERN_VIEW );
    Pubsub.publishSync( Messages.CREATE_LINKED_LISTS );
}

songs.forEach(( song ) =>
    {
        li = document.createElement( "li" );
        li.setAttribute( "data-id", song.id );
        li.innerHTML = "<span class="title">" + song.meta.title + ", by " + song.meta.author + "</span>" +
            "<span class="date">" + Time.timestampToDate( song.meta.modified ) + "</span>" +
            "<span class="delete">x</span>";

        list.appendChild( li );

        handler.addEventListener( li, "click", handleSongOpenClick );
        handler.addEventListener( li.querySelector( ".delete" ), "click", handleSongDeleteClick );
    });

    Pubsub.publishSync( Messages.CLOSE_OVERLAYS, SongBrowserController );
    Pubsub.publishSync( Messages.SHOW_BLIND );
    container.classList.add( "active" );
}