How to use the @magenta/music/node/core.sequences function in @magenta/music

async function warmUpModel() {
  await mvae.initialize();

  // Warm up the model.
  const ns = {notes: [{pitch:60, velocity: 100, startTime: 0, endTime: 1}]}
  const quantizedNS = mmcore.sequences.quantizeNoteSequence(ns, 4);
  await drumify(quantizedNS, 80);

  app.listen(PORT, function() {
    console.log('Your app is listening on port ' + PORT);
  });
}

function fixSequence(ns) {
  // unquantized -> quantized -> unquantized
  const quant = mmcore.sequences.quantizeNoteSequence(ns, 4);
  const unquant = mmcore.sequences.unquantizeSequence(quant);

  for (let i = 0; i < unquant.notes.length; i++) {
    delete unquant.notes[i].quantizedStartStep;
    delete unquant.notes[i].quantizedEndStep;
  }
  delete unquant.totalQuantizedSteps;
  delete unquant.quantizationInfo;

  return unquant;
}