def reduce_to_largest_span(timespan)
      timespan.begin = timespan.begin.sort.first
      timespan.end = timespan.end.sort.last
      timespan
    end
def reduce_to_largest_span(timespan)
      timespan.begin = timespan.begin.sort.first
      timespan.end = timespan.end.sort.last
      timespan
    end
Reduces a timespan with multiple begin or end dates to a single earliest
 begin date and a single latest end date.

 @param timespan [DPLA::MAP::TimeSpan] the timespan to reduce

 @return [DPLA::MAP::TimeSpan] an updated timespan