code: function _error(coreIndex, cores) {
    var errMsg =
      '[cpu-stats] Error: Core "' + coreIndex + '" not found, use one of ' +
      '[0, ' + (cores - 1) + '], ' +
      'since your system has a total of ' + cores + ' cores.';
    console.log(errMsg);
  }
docs: /* PRIVATE