code: function quickDT(obj, zone) {
    // assume we have the higher-order units
    for (const u of orderedUnits) {
      if (isUndefined(obj[u])) {
        obj[u] = defaultUnitValues[u];
      }
    }
  
    const invalid = hasInvalidGregorianData(obj) || hasInvalidTimeData(obj);
    if (invalid) {
      return DateTime.invalid(invalid);
    }
  
    const tsNow = Settings.now(),
      offsetProvis = zone.offset(tsNow),
      [ts, o] = objToTS(obj, offsetProvis, zone);
  
    return new DateTime({
      ts,
      zone,
      o
    });
  }
docs: this is a dumbed down version of fromObject() that runs about 60% faster but doesn't do any validation, makes a bunch of assumptions about what units are present, and so on.