get weekdayLong() {
    return this.isValid ? Info.weekdays("long", { locObj: this.loc })[this.weekday - 1] : null;
  }
Get the human readable long weekday, such as 'Monday'.
Defaults to the system's locale if no locale has been specified
@example DateTime.local(2017, 10, 30).weekdayLong //=> Monday
@type {string}