docs: def make_chunks_from_unused(self,length,trig_overlap,play=0,min_length=0,
      sl=0,excl_play=0,pad_data=0):
      """
      Create an extra chunk that uses up the unused data in the science segment.
      @param length: length of chunk in seconds.
      @param trig_overlap: length of time start generating triggers before the
      start of the unused data.
      @param play:
                  - 1 : only generate chunks that overlap with S2 playground data.
                  - 2 : as 1 plus compute trig start and end times to coincide
                          with the start/end of the playground
      @param min_length: the unused data must be greater than min_length to make a
      chunk.
      @param sl: slide by sl seconds before determining playground data.
      @param excl_play: exclude the first excl_play second from the start and end
      of the chunk when computing if the chunk overlaps with playground.
      @param pad_data: exclude the first and last pad_data seconds of the segment
      when generating chunks
  
      """
      for seg in self.__sci_segs:
        # if there is unused data longer than the minimum chunk length
        if seg.unused() > min_length:
          end = seg.end() - pad_data
          start = end - length
          if (not play) or (play and (((end-sl-excl_play-729273613)%6370) <
            (600+length-2*excl_play))):
            trig_start = end - seg.unused() - trig_overlap
            if (play == 2):
              # calculate the start of the playground preceeding the chunk end
              play_start = 729273613 + 6370 * \
                math.floor((end-sl-excl_play-729273613) / 6370)
              play_end = play_start + 600
              trig_end = 0
              if ( (play_end - 6370) > start ):
                print "Two playground segments in this chunk"
                print "  Code to handle this case has not been implemented"
                sys.exit(1)
              else:
                if play_start > trig_start:
                  trig_start = int(play_start)
                if (play_end < end):
                  trig_end = int(play_end)
                if (trig_end == 0) or (trig_end > trig_start):
                  seg.add_chunk(start, end, trig_start, trig_end)
            else:
              seg.add_chunk(start, end, trig_start)
          seg.set_unused(0)