What is Master in request.user

Hi guys, as tiitle, i dont know master in request.user, how to set master field is true, default is false, i dont know code below in example of docs moralis about validation in cloude function

const validationRules = request => {

  if (request.master) {

    return;

  }

  if (!request.user || request.user.id !== 'masterUser') {

    throw 'Unauthorized';

  }

I think that it is related to using the master key: https://docs.parseplatform.org/cloudcode/guide/