def next_occurring(day_of_week)
      from_now = DAYS_INTO_WEEK.fetch(day_of_week) - wday
      from_now += 7 unless from_now > 0
      advance(days: from_now)
    end
def next_occurring(day_of_week)
      from_now = DAYS_INTO_WEEK.fetch(day_of_week) - wday
      from_now += 7 unless from_now > 0
      advance(days: from_now)
    end
Returns a new date/time representing the next occurrence of the specified day of week.

   today = Date.today               # => Thu, 14 Dec 2017
   today.next_occurring(:monday)    # => Mon, 18 Dec 2017
   today.next_occurring(:thursday)  # => Thu, 21 Dec 2017