code: public void setWeeklyDay(Day day, boolean value)
     {
        if (value)
        {
           m_days.add(day);
        }
        else
        {
           m_days.remove(day);
        }
     }
docs: Set the state of an individual day in a weekly recurrence.
  
  @param day Day instance
  @param value true if this day is included in the recurrence