docs: function compare(a, b) {
    var aMissing = isMissing(a);
    var bMissing = isMissing(b);
    if (aMissing && bMissing) {
      a = MISSING_ORDER[a];
      b = MISSING_ORDER[b];
    } else if (aMissing) {
      return -1;
    } else if (bMissing) {
      return 1;
    }
    return a < b ? -1 : a > b ? 1 : 0;
  }