class Chronic::RepeaterWeekend

def offset(span, amount, pointer)
  direction = pointer == :future ? 1 : -1
  weekend = Chronic::RepeaterWeekend.new(:weekend)
  weekend.start = span.begin
  start = weekend.next(pointer).begin + (amount - 1) * direction * Chronic::RepeaterWeek::WEEK_SECONDS
  Chronic::Span.new(start, start + (span.end - span.begin))
end